The number of soldiers of the Turkish security forces killed in a terrorist attack in northeastern Turkey increased to seven on Monday, a Turkish official said.

Cihangir Guler, sub-governor of Resadiye town of Tokat province, said in a statement that seven gendarmerie troops were killed while three others wounded in an attack perpetrated by terrorists near Sazak Village in Resadiye.

One of the wounded soldiers is in a critical condition, said Guler, adding that he could not provide information on which terrorist organization was responsible for the attack yet.

The Turkish government has been striking hard militants of the outlawed Kurdish Workers' Party (PKK).

Established in 1978, the PKK took up arms in 1984 to create an ethnic homeland in southeastern Turkey. Its separatist campaign has fuelled conflicts that have killed some 40,000 people in the country.

It is estimated that there are a total of 5,000 PKK militants, the majority of whom are holed up in northern Iraq where the PKK headquarters is situated.

The government announced in October that it would reveal a package plan to solve the Kurdish issue by improving democratic rights of the Kurdish group to win over its Kurdish citizens and erode support for the PKK.