ISLAMABAD (Agencies) The border skirmishes heat up as Afghan National Army fired three mortar rounds inside Pakistani territory at Angoor Adda in South Waziristan, while troops killed 40 militants emerged from Afghan side in Mohmand, sources said on Thursday. No loss of life has been reported in the shelling from across the border. However, Pakistan has lodged protest for this unprovoked firing. Briefing media, a military commander said troops backed by jets and helicopter gunships have killed 40 militants in Mohmand area bordering Afghanistan in the past three days. Brigadier Aftab Ahmad told AFP that his forces had destroyed 17 militant hideouts in the Baizai region under his command in the tribal area of Mohmand. Militants were regularly attacking our posts on the Afghanistan border at Shankaro and Mithai and also targeting goods vehicles going to Afghanistan, he said. Brig Ahmad claimed that security forces have strengthened their positions at strategic Shankaro check post and blocked the entry of militants into Mohmand Agency from the Afghan side of the border. Ahmed said militants emerged from Afghan side of the common border and all of them were killed in the operation in which helicopter gunships also took part. Infiltration of the insurgents from the Afghan side into Pakistans tribal region has been completely stopped by regaining control over the Shankaro check post which is key spot to check movement of the insurgents, the operational commander declared. The area from Mithai Valley to Shankaro of Mohmand Agency, bordering Afghanistan, has been cleared of militants and during search operation hideouts of the insurgents were also destroyed, he said. Brig Ahmad said the ground forces used heavy weaponry including artillery and tanks and targeted strongholds of the insurgents during the search drive which continued for three days ago. The operation was launched three days ago with the support of army aviation aircraft, helicopters and fighter jets, Ahmad said. He said several soldiers embraced martyrdom in the operation as the militants in the area showed stiff resistance to the security forces. He said the militants were either killed or forced to run to the other side of the border. The operation commander did not give exact figure of the causalities on the part of security forces. One soldier was martyred when landmine exploded in Shankaro area where the insurgents who had entered into Pakistans territory had laid a network of landmines, Brig Ahmad further said. He said the militants had laid 115 landmines in Shankaro which have been defused. He said army used tanks and heavy guns targeting the militants positions. He expressed the confidence that the insurgents from across the border will not be able to launch attack on the security forces in the Mohmand Agency in future. Major Fazal-ur-Rehman, a spokesman for the paramilitary Frontier Corps, said an operation against militants was launched in three villages in Mohmand region. They were attacking our soldiers from there but now we have cleared these villages (of militants), he said. Rehman said the militants had fled to those villages to escape security crackdowns in other areas. Meanwhile, the Afghan National Army fired three mortar rounds which fell 900 meters inside Pakistani territory at Angoor Adda in sector South Waziristan, according to sources. However, no loss of life was reported. On Wednesday, without any provocation the Afghan troops also fired mortar rounds which fell at Angoor Adda, destroying shops and causing civilian casualties. The attack was retaliated by Pakistani troops immediately. The border clash is ominous as it came at a time when Pakistan-US relations are at their lowest ebb. Earlier this month, Pakistan and Afghanistan had agreed to upgrade a joint commission to expedite the reconciliation process in an effort to restore stability to the region.