KABUL (Reuters) - Two improvised explosive devices (IED) killed five soldiers from NATO-led forces and one civilian in Afghanistan on Friday, the NATO force said in a statement.

Taliban militants have stepped up the level of violence in the country this year, targeting foreign and Afghan military convoys with roadside bombs and suicide attacks.

Four soldiers from NATO's International Security Assistance Force (ISAF) and one civilian were killed by an IED in the northwestern province of Kunar, ISAF said in a statement.

ISAF does not release the nationality of dead soldiers but most of the soldiers in Kunar are American.

The Taliban claimed responsibility for the attack and said it had used a remote-controlled roadside bomb.

Another ISAF soldier was killed on Friday in the eastern province of Khost, ISAF said in a separate statement.

Most of the soldiers stationed in the eastern province bordering Pakistan are also American.

"This is a very difficult time right now, and our sincere condolences and sympathies are with the family and friends of the brave soldiers and civilian who died," said the ISAF spokesman, Captain Mark Windsor, in the statement.

Violence has risen by some 40 percent in eastern Afghanistan this year, ISAF says, because more militants have been able to infiltrate from neighboring Pakistan as a result of de facto ceasefires there between militants and the Pakistani army.

(Additional reporting by Rohullah Anwari in Kunar; writing by Jonathon Burch; editing by Tim Pearce)

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