Turkey's president and opposition discussed Monday a bid by Prime Minister Recep Tayyip Erdogan to curb the powers of judges as he battles a corruption scandal threatening his hold on power.

President Abdullah Gul was holding separate meetings with the heads of the opposition Republican People's Party, Nationalist Movement Party and pro-Kurdish Peace and Democracy Party, NTV channel reported.

Erdogan is seeking to push through a bill that would increase government control over the appointment of judges and prosecutors, despite Turkey's top court calling the measure unconstitutional.

The move was widely seen as an attempt to head off an expanding corruption probe that has seen the arrests of several business allies of Erdogan, as well as the sons of ex-ministers.

The United States and the European Union have weighed in, citing serious concerns over Erdogan's step.

"(I) asked authorities to consult relevant amendments to laws before adoption to make sure they're in line with principles of EU legislation," EU Enlargement Commissioner Stefan Fule said in a tweet on Sunday.

The prime minister, alleging a "judicial coup", has already ordered the sacking of hundreds of police officials involved in the probe, and reshuffled his government after key ministers were forced to resign.

A falling-out between Erdogan and one of his erstwhile backers, US-exiled cleric Fethullah Gulen, whose movement wields influence in the police and judiciary, is said to be behind the crisis.

"We have presented two preconditions to the president. First, the bill should be withdrawn. And second, the political power should not hamper the corruption investigation," Republican People's Party leader Kemal Kilicdaroglu said after his meeting with Gul.

"But if they (Erdogan's government) give us the necessary explanations, then a constitutional change may be on the agenda," he said.

"The bill throws 90 years of democratic gains in the garbage."

Several protests have been held in Ankara and Istanbul calling for Erdogan's resignation, with police firing plastic bullets and tear gas to disperse demonstrators.

Scuffles erupted on Saturday ahead of a second round of debate on the proposals in parliament's justice commission, with politicians throwing punches, water bottles and even an iPad.

The escalating tensions have also exposed a rivalry between Erdogan and Gul, also a former ally, ahead of presidential elections in August.

Gul, who is expected either to be re-elected or be the next prime minister should Erdogan become president, has so far adopted a conciliatory approach toward the crisis and has repeatedly spoken out in support of judicial independence.

Commentators say the president, who is seen as closer to Gulen, is likely to veto the Erdogan's bill.

But since he does not want to openly position himself against Erdogan, he is holding key meetings to iron out the differences until the bill comes his way.

Since the parliament began discussing the bill on Friday, Gul has met with the parliamentary speaker, justice and interior ministers and a deputy prime minister at the presidential palace in Ankara.

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