Ceferin says this showed a "lack of respect" for UEFA referees director Roberto Rosetti, who also briefed lower-level officials from most clubs. UEFA called the session to explain how referees will apply video review of key decisions for the first time in its competitions.
The clubs represented by their first-team coach were Juventus, Lyon, Paris Saint-Germain, Roma and Schalke.
Although two new members of the UEFA executive committee face allegations of financial wrongdoing, President Aleksander Ceferin says there is no reason to block their elections.
Paris Saint-Germain president Nasser al-Khelaifi, who was proposed by Europe's top clubs, is the subject of a criminal proceeding in Switzerland in a wider investigation of financial wrongdoing linked to FIFA.
Ukraine soccer federation Andriy Pavelko won election Thursday despite a campaign at home alerting UEFA to the risk he allegedly poses.
Ceferin says letters UEFA received from former lawmakers and NGOs in Ukraine were "without any concrete proof" or evidence of ongoing court proceedings.
The Slovenian lawyer says "we have to have in mind presumption of innocence."
Al-Khelaifi could be implicated in an independent investigation of PSG's compliance with UEFA financial monitoring rules, and he also heads BeIN Sports, which holds some UEFA broadcast rights. The Swiss case centers on an allegation al-Khelaifi bribed a senior FIFA official to help secure World Cup TV rights.
Ceferin says he understands the potential conflicts of interest for al-Khelaifi "but I don't agree that these are the right concerns."
FIFA President Gianni Infantino says he must balance Europe's wishes with the rest of the soccer world.
Speaking after UEFA President Aleksander Ceferin aimed strong words at him, Infantino said "it's not always easy" for him to work so that "the rest of the world can catch up a little bit" to European soccer.
In an earlier speech to soccer officials, Ceferin explained why he has blocked a $25 billion offer of private investment in new and revamped FIFA competitions that Infantino supports.
Ceferin said honestly disagreeing with FIFA could serve soccer well, and that "yes men" were not helping.
Asked how he received Ceferin's speech, Infantino says "respect goes two ways, and goes also toward the world."
Infantino seems unlikely to get FIFA Council approval for the deal next month in Miami, and says "otherwise, we decide to postpone."
England has retained the FIFA vice presidency reserved for the four British soccer federations ahead of a possible 2030 World Cup bid.
UEFA member voters gave Greg Clarke a 37-18 win over David Martin, the Northern Ireland federation president.
Clarke takes the FIFA Council seat held by David Gill, the former Manchester United CEO. Gill has stepped down from his FIFA duty but remains on the UEFA executive committee.
The four British federations and Ireland are exploring a possible bid to host the 2030 World Cup. That decision is scheduled for 2023.
The controversial president of Ukraine's soccer federation has been elected to a seat on UEFA's executive committee, helped by lobbying from former Olympic champion Sergei Bubka.
Andriy Pavelko won votes from 27 of 55 UEFA member federations to gain one of the 19 positions on European soccer's policy-making panel.
Pavelko, who has led the Ukrainian soccer body since 2015, has been under scrutiny from claims of alleged financial wrongdoing in his home country.
Bubka, the pole vault great who is an IOC member, was part of the Ukraine delegation at the UEFA meeting.
Ukraine retains its place on UEFA's highest committee which was held by Grigoriy Surkis, the former Dynamo Kiev president, who stood down after 15 years.
Albania federation president Armand Duka also was elected, with 36 votes.
Former Bulgaria goalkeeper Boris Mihailov lost his seat with only 25 votes.
UEFA says it will launch its own streaming service to broadcast soccer games to more fans worldwide.
UEFA President Aleksander Ceferin says the over-the-top (OTT) platform will start in the next six months.
Ceferin says UEFA is working with technology companies, like new commercial partner Alibaba, to develop ideas.
In his acceptance speech after being elected for four more years, Ceferin says he wants UEFA to be a "source of constructive ideas to FIFA instead of one of opposition."
Other key targets Ceferin has outlined for the next four years include a European bidder winning the 2030 World Cup hosting rights and updating financial fair play rules which monitor club finances.
Aleksander Ceferin has been formally re-elected as president of UEFA by acclamation.
The Slovenian lawyer was unopposed and will lead European soccer for four more years. His presidency began in September 2016.
Ceferin's first 2½ years in office completed the mandate of predecessor Michel Platini, who has banned by the FIFA ethics committee for financial irregularities.
UEFA President Aleksander Ceferin says he won't be a "yes man" supporting FIFA's push for a $25 billion deal to create and revamp competitions.
With FIFA President Gianni Infantino in the audience, Ceferin says UEFA is showing respect for soccer by saying it disagrees with the world soccer body's proposal.
Infantino has spent the past year promoting the offer from private investors to revamp the Club World Cup and create a global Nations League tournament.
Ceferin has blocked the secretive plan in testy meetings of the FIFA Council, which will meet in Miami next month.
Ceferin says "it is often the yes man who lures leaders to their demise," and that respect means disagreeing with friends "when we think in all humility that they are wrong."
Earlier in his speech ahead of his unopposed re-election, Ceferin said he has had doubts and made mistakes since taking office in September 2016.
Ceferin says "a leader without doubts is a delusional and dangerous leader."
UEFA President Aleksander Ceferin says he is working with European Club Association leader Andrea Agnelli to protect the Champions League from any breakaway threats.
Ceferin says "while we lead these two organizations there will be no Super League. It is a fact."
Speaking to European soccer officials on Wednesday ahead of his unopposed re-election, Ceferin recalls a group of elite clubs were considering a split in 2016 before he was voted UEFA president.
Ceferin says if clubs had split from the Champions League "they would have lost their status as great clubs in the hearts of the people. The only thing great about you would be your past."
The Slovenian official tells the clubs "trust me, you will not regret" taking a stand against cynicism and greed.
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