Facebook unveiled new tools on Monday to counter online political meddling in the European elections, part of a campaign to answer growing pressure to rein in disinformation.

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

The new rules will require a wide range of political ads linked to the European elections on May 23 to 26 to be specifically authorised and tagged with a clear "paid for by" disclaimer.

Clegg said these tools will also cover so-called issue ads "which don't explicitly back one candidate or political party but which focus on highly politicised topics like immigration."

Those ads will then be stored on servers for up to seven years, along with the details of their reach and specific data on the buyer of the advertising.

The measures come after a nightmare year for Facebook, marked by a series of scandals over data protection and privacy and concerns that the leading social network had been manipulated by foreign interests for political purposes.

Criticism of Facebook has included allegations that the social network being used as a platform to spread divisive or misleading information, as was the case during the 2016 election that put US President Donald Trump in the White House.

Facebook ads have also been at the centre of the FBI investigation over Russia's alleged meddling in the US election of Trump and suspicions are rife that the Kremlin has intervened in votes across Europe.