The incident occurred as tensions had appeared to ease over the barring of several prominent Kurds from running in upcoming parliamentary elections after the Higher Electoral Board (YSK) signalled that it might reverse its ruling.

Selahattin Demirtas told Anatolia news agency that one person was killed and several injured in Bismil town, where Kurds were holding a demonstration to protest the disqualification of their candidates.

Local officials contacted by AFP could confirm only several injured people, among them three in serious condition, while a witness reported seeing one dead and hospital sources in the regional capital Diyarbakir said the body of a young man had been brought from Bismil.

Witnesses in Bismil said the young man died when police opened fire first with plastic bullets and then with live rounds.

Other witnesses said police opened fire when demonstrators hurled petrol bombs at the security forces.

Military units tightened security around government buildings in the town, where all shops and working places were shut as the clashes went on.

"I have informed (the president) that I cannot go to Ankara in the current circumstances," Demirtas told Anatolia in Diyarbakir.

President Abdullah Gul had invited Demirtas for talks at his residence late Wednesday in an effort to ease tensions over the barred candidates.

The YSK was expected to reverse its decision for at least some of the seven candidates after unnamed officials of the body, quoted widely in the media, signalled that the presentation of additional documents would help overcome the problem.

Anatolia news agency quoted the deputy head of the YSK, Kirdar Ozsoylu, as saying that he hoped the board will decide "in favor of democratic rights and fundamental freedoms."

Lawyers for four of the candidates submitted the requested papers to the board, with others expected to follow later in the day, media reports said.

Among the first four was iconic Kurdish activist Leyla Zana, winner of the European Parliament's human rights award who spent 10 years in jail before being released in 2004.

Zana obtained a court document certifying that there were no legal restrictions on her political rights, Anatolia said.

In a move threatening to fan Turkey's long-standing ethnic conflict, the YSK Monday disqualified 12 candidates from the June 12 parliamentary elections, among them seven people backed by the Peace and Democracy Party (BDP), Turkey's main Kurdish political movement.

The barring of their candidates deepened a sense of injustice among Kurds, whose political parties already face a series of legal hurdles.

The board based the decision on past convictions of the bidders and legal technicalities, but came under fire in Wednesday's press for disregarding recent legal amendments that favour the applicants.

The barred candidates include other prominent Kurdish figures, among them two members of the outgoing parliament.

The BDP has urged an extraordinary parliamentary session to tackle the controversy and threatened to boycott the polls.

Thousands of Kurds took to the streets across Turkey Tuesday to protest the decision, clashing with riot police and throwing petrol bombs at public buildings and banks.

On Wednesday again there were brief clashes in Diyarbakir that landed at least 16 protestors in police custody and left four others slightly injured, an AFP reporter said.

The BDP fielded its candidates as independents in order to circumvent an electoral threshold under which parties have to get at least 10 percent of votes to enter parliament.

The ruling Islamist-rooted Justice and Development Party, aiming for a third straight term in power, has rejected widespread appeals to lower the threshold.