The Higher Electoral Board (YSK) is 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.

Gultan Kisanak, already a lawmaker in the outgoing parliament, was the first to submit her papers to the YSK through a lawyer, with others expected to follow later in the day, Anatolia news agency reported.

The YSK dropped a bombshell Monday as it 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.

It 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 prominent Kurdish figures, among them Leyla Zana, winner of the European Parliament's human rights award who spent 10 years in jail before being released in 2004.

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.

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

The BDP urged an extraordinary parliamentary session to tackle the controversy and threatened to boycott the polls if their concerns are not unresolved.

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 (AKP), aiming for a third straight term in power, has rejected widespread appeals to reduce the threshold.

Analysts say the disqualification of BDP-backed candidates is likely to play into the hands of the AKP, which also enjoys strong popularity among the Kurds.