The soldier was killed in a clash overnight Sunday in Yayladag in Bingol province where the army has been pursuing an operation against militants from the separatist Kurdistan Workers' Party (PKK) since the weekend.

Two rebels were shot dead in the same region Monday after they refused orders to surrender and fired on Turkish forces, the sources added.

Three PKK rebels were killed in a separate security sweep in the neighbouring Tunceli province.

The latest clashes bring to 10 the number of members of Turkish security forces killed in two days of heavy fighting in the country's east and southeast, in one of their heaviest losses in months.

Recent media reports have said that the Turkish army has sent reinforcements to the restive southeast and east to counter PKK rebels infiltrating into Turkish territory from their bases in the mountains of northern Iraq with the arrival of spring.

Turkey says thousands of PKK rebels have found refuge in the mountainous enclave where they are able to easily obtain weapons and explosives to be used in attacks in Turkey.

In the southeastern province of Sirnak, which lies on the border with Syria and Iraq, police seized bombs made from eight kilograms (about 18 pounds) of plastic explosives and arrested three suspected PKK rebels, the local governor said Monday.

"We are continuing the investigation to find out the suspects' connections in the west of the country," Selahattin Apari told a press conference, the Anatolia news agency said.

More than 37,000 people have been killed since 1984 when the PKK, which is considered a terrorist organisation by Turkey, the European Union and the United States, took up arms for self-rule in the mainly Kurdish southeast of the country.

The PKK announced a ceasefire in October, but Turkish authorities rejected it.