KABUL (Agencies) - Nato in Afghanistan spoke out Sunday against Pakistan's moves to reach peace deals with Taliban militants on its side of the border, saying that peace talks have already led to an increase in insurgent attacks in Afghanistan. Nato spokesman Mark Laity urged Pakistan to avoid agreements that "put our troops and our mission under threat," with peace talks on that side of the border linked to an increase in attacks in Afghanistan and said Islamabad must take the alliance into account when it makes such deals. "We have seen increased activity in the eastern part of the country especially, which we believe can only be attributed to the de facto ceasefires and a reduction of Pakistani military activity," he said. "We respect the sovereignty of Pakistan absolutely but it's important they take into account the need to ensure that any agreements they make do not lead to an increase in violence in Afghanistan," he said. "They have a sovereign right to make agreements," Laity said at a Press conference, adding however, "We have a right to answer if those agreements put our troops and our mission under threat. "It is no real solution if trouble on one side of the Durand Line (the border) is merely transferred to the other side." Laity said Nato believed an increase in militant activity along the eastern border with Pakistan could only be attributed to a reduction in the Pakistani army's efforts against militants because of the peace talks. British Defence Minister Des Browne, on a visit to Afghanistan, said he understood the agreement between Pakistan and the Taliban included an undertaking that the militants would not export violence to Afghanistan. "Now it's the Pakistan government's responsibility to ensure that that aspect of the agreement is enforced," he told reporters. "It might be very difficult on that part of the border to enforce it, but it is their responsibility." Afghan Defence Ministry spokesman General Mohammad Zahir Azimi told the same media briefing that Pakistan territory "should not be used to kill innocent people in Afghanistan." "Previous peace accords between Pakistan's government and insurgents have shown that it was a golden time for insurgents - they got equipped, they got ready and they launched operations against both governments," he said. He said Kabul was sending a high-level delegation to Pakistan in the coming days to voice its concerns over peace deals. "The people of Afghanistan and the government of Afghanistan are concerned regarding the announcement of Baitullah Mehsud and we hope Pakistan territory is not used against the people of Afghanistan, isn't used to kill our innocent people," Azimi said. Four visiting US Congressmen said after talks with Afghan President Hamid Karzai that they would raise concerns about the peace deals with militants during a visit to Islamabad. They also said they were concerned that Islamabad's peace talks with militants could preclude a rise in attacks in Afghanistan. The Democratic lawmakers said part of their reason for visiting Kabul and Islamabad was to look into the issue of extremist "sanctuaries" on the Pakistan side of the border. There was widespread concern about the deals, said one of the lawmakers, Ben Nelson, a US Senator from Nebraska. "They are protected in their sanctuaries and yet they come into Afghanistan and take on the activities of terrorists," he said. Nelson said the United States needed to focus on Afghanistan "a little more," and this could include boosting its troop numbers as "Taliban and terrorists" arrive from across the border. There was also a need to protect farmers in the opium-producing south so they could turn from growing opium poppies to cultivating food, he said. Nelson was accompanied by Florida Representatives Allen Boyd and Timothy Mahoney, as well as Representative Nick Lampson of Texas. They are also due to visit New Delhi and Islamabad.