| Kurdish fighters have been at the centre of media speculation over Sunday's blast in Istanbul's city centre [AFP]
Kurdish fighters have denied responsibility for a suicide bomb attack in Istanbul that wounded 32 people and announced the extension of a unilateral ceasefire.
But Sunday's bombing in Taksim Square coincided with the end of the PKK's previous ceasefire, leading to suspicions that the group may have been behind the attack.
But in a statement through a Kurdish news agency on Monday, the PKK, or Kurdistan Workers' Party, rejected those claims and also said it was extending a truce until Turkey's general elections in 2011.
"There is no way we would be involved in such an attack on a day our organisation was getting ready for a step towards peace and a democratic solution," the PKK said in a statement, carried by the Firat news agency.
It also said it was extending a month-old ceasefire that expired on Sunday until parliamentary elections, due to take place in June 2011.
"Neither us nor any organisation linked to us have carried out or planned such an attack ... We have no connection with the attack in any way," the statement said.
The government has said it is too soon to conclude which group was behind the attack.
Besir Atalay, Turkey's interior minister, said no one had been detained in connection with the attack, but police had information on who may have carried it out, which would be disclosed once the authorities were sure who was to blame.
The suicide bomber, who has not been identified, blew himself up near riot police stationed at Taksim Square, a popular location in central Istanbul for shoppers, tourists and demonstrators. Most of the seriously wounded were police officers.
|Extreme leftwing groups have carried out attacks in Istanbul in the past [File: AFP]
Kurdish fighters, al-Qaeda and leftwing extremists have all carried out attacks in Turkey.
Small PKK cells have staged attacks in the past without authorisation from PKK headquarters and splinter groups comprised of former members have carried out bombings also.
The Kurdistan Freedom Hawks, a group believed to have PKK links, has claimed responsibility for urban bomb attacks in recent years.
A high-ranking security officer in western Turkey told the Reuters news agency that techniques used in Sunday's attack showed a "90 per cent probability" the PKK was responsible.
The officer said investigators believed there was also a small chance the attack was the work of leftists, but "al-Qaeda and other organisations are out of the picture".
The PKK is considered a terrorist group by Turkey, the US and the European Union. The group has been fighting for autonomy in southeastern Turkey in a conflict that has killed tens of thousands of people since 1984.
Turkey has recently taken steps to improve the rights of Kurds, who make up 20 per cent of Turkey's population, including allowing Kurdish-language television broadcasts.
The government has also increased contacts with the Kurds as part of a campaign to end the conflict, though it maintains an official policy of not talking to the group.
"Despite all our requests, all our warnings, all the documents we hand over to them, certain countries do not refrain from giving direct or indirect support to terrorism"
Recep Tayyip Erdogan, Turkish prime minister
Omer Celik, a senior government legislator, dismissed on Monday the extension of the PKK ceasefire, saying "the government will not alter its course in the struggle against terrorism based on decisions taken by the [rebel] organisation".
"However, if it means that less people will be killed, then it is good in that sense," he told Turkey's private NTV television news network, adding that the government was "sincerely" seeking a peaceful end to the conflict.
Recep Tayyip Erdogan, Turkey's prime minister, said on Monday that some European countries were not doing enough to help it fight terrorism.
He did not name the countries, but Turkish officials have said the PKK raises funds through extortion or other criminal activities in European countries such as Germany that have a large number of Kurdish immigrants.
"We now want concrete steps, concrete results," Erdogan said. "Even today, in certain European countries, organisations with known ties to the terrorist organisation freely operate under the guise of associations, foundations, or the media.
"Despite all our requests, all our warnings, all the documents we hand over to them, certain countries do not refrain from giving direct or indirect support to terrorism."