Syria pledged on Sunday to fully cooperate with a UN investigation into the assassination of former Lebanese Prime Minister Rafik Hariri, saying the terms of the cooperation had been agreed on last month with the new head of the inquiry. Syrian Foreign Minister Walid Moallem also said his country would step up diplomatic activity to counter intense US-led international pressure on Damascus over its policies in Iraq and the Arab-Israeli conflict. Serge Brammertz, head of the UN inquiry into Hariri's killing, made his first visit to Syria last month and discussed the commission's work with Moallem. "We will cooperate with this commission. We have agreed on the basis of this cooperation (during Brammertz's visit)," Moallem said in an interview with Lebanon's Al Manar television Sunday. "We believe that as long as Mr. Brammertz leads his investigation in a professional way, he will get full Syrian cooperation."