A day after the arrest of former Bulgarian Prime Minister Boiko Borissov, the judiciary no longer links his detention to a misuse of EU funds.

The public prosecutor's office in Sofia announced on Friday that the pre-trial investigation into suspicion of extortion was ongoing and that the EU public prosecutor's office was excluded.

This contradicts an original information from the Ministry of the Interior, which has since been removed from the website.

The former head of government and chairman of the largest opposition party GERB was arrested on Thursday evening.

There were no specific allegations.

It should be clear on Friday evening whether he will be released or whether he will have to remain in custody.

In the Borisov case, Prime Minister Kiril Petkov was heard on Thursday, as he announced on Friday.

Finance Minister Assen Vasilev attributed Borisov's arrest to a tip-off by a Bulgarian gambling magnate living in exile in Dubai, against whom 18 charges have been brought in Bulgaria.

He accuses Borisov and former Finance Minister Vladislav Goranov, who was also arrested on Thursday evening, of extortion.

Borisov's former media adviser Sevdalina Arnaudowa was also arrested, but not the head of the parliamentary budget committee, Menda Stoyanova, as it was originally called.

Supporters of Borisov's GERB party and the parliamentary faction demanded his release during protests at the seat of government and in front of parliament.

They demanded new elections.

EU Attorney General Laura Kövesi said during a visit to Sofia on Wednesday and Thursday that there were indications of 120 cases of misuse of EU funds in Bulgaria.