Romania's parliament gave the go-ahead on Wednesday to corruption inquiries into former Prime Minister Adrian Nastase, after long delays in the case angered the European Union.

Since Romania's entry to the EU in 2007, the European Commission has demanded the poor Black Sea state speed up top-level investigations to prove it is serious about addressing graft.

Deputies approved by 158 to 128 votes the request to launch two separate investigations into Nastase, who ran a leftist cabinet between 2000 and 2004.

The politician says he is innocent and accuses prosecutors of being politically motivated.

Prosecutors have said they suspected Nastase of blackmail and taking bribes worth 1.4 million euros, as well as giving bribes to cover up potential abuse while he was in office.

He already faces trial on charges of siphoning state cash to finance his 2004 presidential election campaign.

The vote is a victory for the ruling centre-left coalition, which won power in a November election.

"This vote is important because it is giving credibility to the institution of parliament. Now the files go to justice and I hope it will be fair justice," lower house speaker Roberta Anastase told parliament.

Non-governmental organisations and diplomats say too many politicians are entangled in powerful interest groups that oppose efforts to curtail corruption.

The European Commission has urged Romania to do more to fight corruption ahead of a full-year EU assessment in July.