Seven Turkish police officers were killed and at least 27 people wounded on Thursday in a bomb attack on their vehicle in the Kurdish-majority southeastern city of Diyarbakir that President Recep Tayyip Erdogan warned should show the world the "true face" of terror in the country.

The attack blamed on Kurdish militants took place on the eve of a rare visit by Prime Minister Ahmet Davutoglu, whose government has waged a relentless campaign against Kurdish rebels since last summer, to central Diyarbakir on Friday. 

Three Turkish soldiers were killed Wednesday in clashes with Kurdistan Worker's Party (PKK) militants in Diyarbakir in southeast Turkey, the military said, as a controversial curfew order was expanded to new areas in the Kurdish-dominated city.

Kurdish militants on Wednesday attacked the security forces with rifles and rocket launchers in the central Sur district of Diyarbakir, prompting intense clashes that killed three soldiers and wounded six others, the army said in a statement.

Five children were wounded on Friday when suspected militants hurled a hand-made explosive device into a schoolyard in majority-Kurdish southeast Turkey, security sources said, blaming the attack on the Kurdistan Workers Party (PKK).

The blast ripped through the yard of a secondary school in the Baglar district of Diyarbakir province where students had gathered during a classroom break, a security source told AFP.

Two protesters were killed Monday in clashes with police in Turkey's mainly Kurdish southeastern city of Diyarbakir amid growing tensions over a days-long curfew, security sources said.

The two demonstrators, aged 21 and 25, were shot dead in violent clashes that erupted over the curfew that has been in place in the city's central Sur district almost uninterrupted since December 2, a security source told AFP, asking not to be named.

A Turkish soldier was killed in southeastern Diyarbakir province in a new attack blamed on the rebel Kurdistan Workers' Party (PKK), a security source said.

Sergeant Mehmet Ali Sarak, 25, came under fire from PKK militants with automatic rifles while on his way to his army base in the Silvan district of Diyarbakir, the source told AFP on condition of anonymity.

Turkey on Friday detained 251 people in coordinated nationwide dawn raids against suspected Islamic State (IS) jihadists and Kurdish militants following a wave of deadly violence in the country, the prime minister's office said.

"A total of 251 people were taken into detention for belonging to terrorist groups," the statement said, adding that the raids took place in 13 provinces across Turkey.

One Turkish policeman was shot dead and another badly wounded in an attack by armed men in Turkey's majority Kurdish-city of Diyarbakir, hospital sources told AFP.

The attack happened while the police were carrying out a routine traffic check in the southeastern city, a day after two police were shot dead in an attack claimed by Kurdish militants, reports said.

The death toll from an attack on a rally of Turkey's pro-Kurdish People's Democratic Party (HDP) rose to four on Saturday, when a 65-year-old died from his wounds, the Dogan news agency said.

The June 5 attack on an HDP pre-election rally in the southeastern city of Diyarbakir, caused by a bomb stuffed with ball bearings, came two days ahead of the June 7 legislative elections in which the party scored a major breakthrough.

Turkish authorities have detained 17 people over clashes between rival Kurdish groups that left four people dead and inflamed tensions in Turkey's main Kurdish city days after legislative elections, officials said Wednesday.

The violence broke out in Diyarbakir on Tuesday when Aytac Baran, the leader of a charity linked to the Kurdish Islamist political party Huda Par, was shot dead, prompting a gunfight that left three more people dead and 11 injured.

Three people were killed Tuesday, including the leader of an Islamist charity, in clashes between rival Kurdish groups in Diyarbakir, the interior ministry said, adding to tensions in Turkey's largest Kurdish-populated city days after legislative elections.   

Aytac Baran, the leader of the Ihya-Der charity group, was shot dead by unknown gunmen outside his home in Diyarbakir, prompting a gunfight that left two others dead.