Parliament, scheduled to convene at 3:00 pm (1200 GMT), was expected to overwhelmingly back the motion that gives the government another year-long mandate for cross-border operations against the outlawed Kurdistan Workers' Party (PKK).

Apart from the Democratic Society Party, the country's main Kurdish political movement -- all parties support striking at the rebels inside their Iraqi strongholds amid nationwide outrage over Friday's deadly attack on a military outpost near the border.

In what was the bloodiest fighting this year, a large group of rebels used the cover of heavy weapons fire from northern Iraq in their strike in Hakkari province.

Ensuing clashes killed twenty-three militants. Two more rebels were killed Monday in continuing security operations in the area, the army said.

A soldier died in hospital Wednesday in Diyarbakir, the main city of the Kurdish-majority southeast, succumbing to injuries from clashes the previous day, officials said.

In another incident, a small explosion -- believed to be caused by a homemade bomb -- occurred Wednesday outside an office of the ruling Justice and Development Party in downtown Istanbul, causing minor damage, Anatolia news agency reported.

There was no immediate word about the perpetrators.

Speaking ahead of the parliamentary vote, Prime Minister Recep Tayyip Erdogan stressed Turkey's right to self-defence and said Ankara would launch a cross-border incursion if necessary to rout the rebels.

Such an operation will be carried out "if need be, at the right time and under the right conditions with a view of obtaining the right result," Erdogan said Tuesday.

"The sole target of a possible cross-border operation will be the terrorist organisation," he said, referring to the PKK.

Under the current mandate that expires October 17, the Turkish army has carried out several air strikes in northern Iraq as well as a week-long ground incursion in February.

The operations were backed by intelligence from the United States which nonetheless fears that a large-scale Turkish intervention could destabilise Iraq's relatively calm north.

Since January, Turkish forces have killed 640 PKK militants, about 400 of them in cross-border operations in northern Iraq, according to army figures.

Ankara charges that about 2,000 PKK rebels are holed up in the autonomous enclave where they allegedly enjoy free movement, are tolerated by the region's Kurdish leaders and obtain weapons and explosives for attacks in Turkey.

Iraqi authorities have repeatedly pledged to curb the PKK, but say the group takes refuge in mountainous regions to which access is difficult.

The PKK -- considered a terrorist group by Turkey, the United States and the European Union -- has been fighting for self-rule in the mainly Kurdish southeast and east of Turkey since 1984. The conflict has claimed some 44,000 lives.