Istanbul bomb rocks bus carrying soldiers, 4 dead

A roadside bomb rocked a bus carrying military personnel and their families in Turkey's largest city of Istanbul on Tuesday, killing four, after the Turkish army stepped up operations against Kurdish rebels.

The remote controlled bomb was detonated near a military housing complex in the district of Halkali. Three of those killed were sergeants, the fourth victim was a 17-year-old girl, state news agency Anatolian said.

The blast wounded nearly a dozen people and two were in a serious condition, Istanbul's provincial governor Huseyin Avni Mutlu said.

"This is a terrorist attack, and the aim of the attack is clear -- to create divisions, tensions and despair," he told reporters.

There was no immediate claim of responsibility.

Kurdish separatists, based in northern Iraq, have increased attacks on military installations in Turkey's mainly Kurdish southeast, but the group has carried out attacks in large cities in the past. Leftist groups and Islamist militants have also carried out bomb attacks in Istanbul in the past.

Istanbul on Tuesday was hosting a summit of southeast European leaders, including Croatian, Serbian and Turkish foreign ministers.

Turkish military forces began a major deployment of troops and elite forces along the border with Iraq on Monday, as fighting has intensified between Turkish military forces and militants of the illegal Kurdistan Workers Party (PKK).

Television channels showed images of the bus's shattered windows and of the wounded being taken to hospital after the blast, at about 7.30am (0430 GMT).

It was not clear how many passengers were on the bus or how many were military personnel.

Prime minister Tayyip Erdogan, who has said Kurdish militants would "drown in their own blood", faces mounting criticism for his government's failure to stop the escalation in violence.

PKK guerrillas killed 11 soldiers at the weekend and one soldier was killed on Monday when Kurdish separatists opened fire on two military police units.

The PKK said this month it had scrapped a year-old unilateral ceasefire and resumed attacks against Turkish forces because of military operations against it.

Some 40,000 have been killed since 1984 when the PKK took up arms to carve out an ethnic homeland in mostly Kurdish southeastern Turkey.