Romanian Senate speaker Crin Antonescu has taken over the reins as interim head of state Tuesday after Romania's top court on Monday approved Traian Basescu's controversial suspension by lawmakers.

The move comes ahead of a 29 July referendum to validate last week's parliamentary vote to impeach the centre-right Basescu in a political and constitutional feud that has set off alarm bells among Romania's EU partners.

Romania's constitutional court is also due Tuesday to rule on amendments backed by Prime Minister Victor Ponta's coalition on the terms of the referendum, which analysts say are expected to make it easier to impeach Basescu.

Antonescu, a member of Ponta's centre-left coalition, was only last week appointed the head of the senate in controversial votes that saw both opposition speakers ousted.

The EU again Tuesday voiced its concern about the situation in Romania, one of Europe's poorest countries which joined the bloc five years ago.

European Commission spokeswoman Pia Ahrenkilde Hansen said the EU executive's president Jose Manuel Barroso would meet Ponta on Thursday in Brussels to discuss the latest developments.

"We remain concerned about the speed and the consequences of decisions taken in recent weeks, and we have many questions regarding the respect for the independence of the Constitutional Court and the judiciary," she said.

She noted however that the court had confirmed that the parliament had used the correct procedures in suspending Basescu, a former sea captain who had been president since 2004.

On Friday, 256 out of 432 deputies voted to impeach Basescu over claims he improperly assumed the powers of the prime minister when he announced drastic austerity cuts in 2010.

Ponta has been feuding with Basescu since his Liberal Social Union (USL) coalition took office in May after wresting power from a government led by the centre-right Liberal Democratic Party (PDL) following a no-confidence motion.

He said Monday's ruling by the country's top court confirmed that "the government and the parliament respected the rules of democracy".

The court, which has complained of "virulent attacks" against it by the government, ruled that a law passed by deputies limiting its power to intervene in parliamentary decisions was unconstitutional.

But it said objections by the PDL over the legality of last week's sacking of the speakers of both houses of parliament—posts both held by the opposition party—were not admissible.

The situation in Romania, which joined the EU five years ago, has triggered concern in fellow EU members including Germany as well as the United States and rights groups.

German Chancellor Angela Merkel warned Romania on Monday of "consequences" following the parliament impeachment vote which her spokesman had branded "unacceptable".

Ponta brushed off the criticism, saying it was up to the people of Romania to decide on the impeachment in a "democratic vote".