The European Union has urged US internet giants and advertising firms to intensify the fight against disinformation campaigns before EU elections in May, or risk regulation.

The European Commission said Google, Facebook, Twitter, Mozilla and advertising groups have made "some progress" toward meeting their pledges to fight fake news by removing bogus accounts and curbing suspect sites.

However, "the pace of progress needs to be faster," the EU's security commissioner, Julian King, said just four months before elections for a new European Parliament.

"We cannot afford to wake up the day after the elections and find we could and should have done more," Mr King told a press conference in Brussels.

The European Commission, the 28-nation union's executive arm, gave its first report on what the internet players have done to meet pledges made late last year in a "code of practice" to fight disinformation.

The commission said "additional action is needed to ensure full transparency of political ads" by the start of the election campaign in EU member countries.

It also urged platforms to give European researchers access to their data, something Mr King said leading researchers claim Facebook has failed to do.

The commission called on the platforms to ensure cooperation with member countries through the Rapid Alert System.

The system, which is planned for March, will allow members to share data and analysis on propaganda campaigns and promote what the bloc says will be objective communications about its values and policies.

Mariya Gabriel, the commissioner for digital economy and society, said internet players must intensify their monitoring and reporting while increasing cooperation with fact checkers and researchers.

"The time for fine words is over," Gabriel told the press conference.

Facebook came under the biggest spotlight in the commission report despite unveiling new tools on Monday to counter online political meddling.

The US tech giant's vice president, former British deputy prime minister Nick Clegg, said in Brussels that the methods would become available in late March and help "make political advertising on Facebook more transparent".