According to the BBC, the party's critic on Europe, Mark Francois, said that he, opposition foreign affairs critic William Hague and the leader of the Tories in the European Parliament, Timothy Kirkhope, on Wednesday (11 March) visited the chairman of the EPP, Joseph Daul, in Strasbourg to inform him of their intentions.
Tory leader David Cameron in 2005 during his leadership campaign had pledged to leave the parliament's centre-right political family due to his party's disagreement with its support for the Lisbon Treaty and, more generally, for its euro-federalist orientation.
Though the British Tories are committed to remaining in the European Union, euroscepticism has long flourished amongst their members of parliament, their voters and the conservative press in the UK.
Nevertheless, the length of time Mr Cameron has taken to fulfil his promise led some to believe he would not carry it out.
The move would also severely restrict the UK Tories participation in considering European legislation. The EPP is the largest grouping in the parliament and is expected to remain so after the June European elections.
Outside the EPP, the UK party will have considerably reduced influence in the chamber.
The UK public broadcaster reports that it has been told that the Tories intend to leave the EPP in May ahead of the elections and will form an entirely new political grouping in the parliament after the results are known.
Until now, speculation had suggested that if the Tories were to leave the EPP, they might join the second conservative grouping in the parliament, the Union for a Europe of the Nations (UEN).
The UEN is an uncomfortable amalgam of centre-right parties such as Ireland's Fianna Fail and hard-right parties such as Italy's xenophobic Northern League and the post-fascist Alleanza Nazionale.
However, Fianna Fail is set to leave the UEN after the elections and join the centrist Alliance of Liberals and Democrats in Europe (ALDE), while the Italian the post-fascist Alleanza Nazionale has merged with Italian Prime Minister Silvio Berlusconi's People of Freedom party, which is a member of the European People's Party, and will thus join the EPP in July.
"The meeting was amicable and during the course of it, we confirmed to Mr Daul our long-standing intention to leave the EPP and establish a new grouping in the European Parliament after the 2009 elections," said Mr Francois.
The BBC reports that the new political family in the parliament may be called 'European Conservatives'.