A leftist group has claimed responsibility today for bomb and missile strikes on Turkish government and ruling party offices which Turkey's prime minister said were aimed at derailing a peace process with Kurdish rebels.

The Revolutionary People's Liberation Party-Front (DHKP-C) said its members attacked the Justice Ministry and offices of the ruling AK Party with hand grenades and a shoulder-fired missile in the capital Ankara.

"The AKP rules the people with police and judicial terror ... To those who constantly enforce terror, the people's justice will one day knock on your door," a statement posted on a website close to the DHKP-C said.

The blasts preceded an anticipated ceasefire call tomorrow by jailed Kurdish militant leader Abdullah Ocalan.

He has been negotiating with state officials to end a 29-year conflict that has killed 40,000 people, limited economic growth and undermined Turkey's bid for European Union membership.

The truce call, expected to coincide with the Kurdish New Year, would be a big step in what is shaping up to be the most serious effort yet to end the bloodshed with Ocalan's Kurdistan Workers Party (PKK) militants.

The struggle with the PKK, deemed a terrorist group by the United States and the European Union as well as Ankara, is Turkey's primary domestic security concern and there are forces on both sides opposed to a resolution.

Turkish Prime Minister Tayyip Erdogan condemned the attacks and vowed to press on with the peace process.

"The attacks, which were carried out while an extremely critical and sensitive process is going on, are very clearly attacks on democracy, the settlement process, national will and brotherhood," Erdogan said during a visit to Denmark.

"These attacks also show how correct a path we are on in terms of democratisation and the settlement process. Despite all these elements that are uncomfortable with brotherhood, democracy and law, we will carry on resolutely," he said.

The DHKP-C and PKK were formed in the 1970s with similar leftist ideologies, although the former pursued a virulently anti-American and anti-imperialist path while the latter focused on Kurdish identity.

The two have cooperated in the past and the DHKP-C would have little to gain from a peace settlement between Turkey and the PKK.

"Who are you deceiving? What 'settlement', what 'peace' are you talking about in our country where the people are woken daily by (police) operations?" the DHKP-C statement said.

Turkish police have detained more than 100 people in a series of operations against the DHKP-C since January, most recently seizing 12 people.

ISTANBUL ATTACKS

In Diyarbakir, the largest city in the mainly Kurdish southeast, the region's main pro-Kurdish party was making final preparations for the Kurdish New Year "Newroz" celebrations which tens of thousands of people were expected to attend.

"We will fulfil properly every duty which our leader (Ocalan) gives to us," the PKK said in a statement to mark the celebrations. But it complained that Turkey's armed forces had bombarded areas where PKK fighters are located in northern Iraq on Tuesday with artillery shells and mortar bombs.

The DHKP-C has carried out retaliatory attacks before for arrests of its members and has become more prominent in recent months as the PKK peace process has advanced.

Early today, a small bomb exploded near state offices in Istanbul, Turkey's business and cultural hub, damaging windows but injuring no one. Police defused separate explosives in front of a cultural centre in the city.

The DHKP-C statement did not mention the Istanbul attacks.

Interior Minister Muammer Guler said earlier there was a "strong probability" that the DHKP-C, one of whose members blew himself up at an entrance of the USembassy on February 1, killing a Turkish guard, was responsible.

"Various groups that we know to be against the (peace) process could have chosen these targets," Deputy Prime Minister Bulent Arinc told reporters. "I think this could have been done to frighten and intimidate the public."

The pro-Kurdish Peace and Democracy Party (BDP), which is involved in the peace process, condemned the Ankara attacks.

- Reuters