Pakistan began deploying thousands of additional troops to its border with India on Friday amid rising tension in the aftermath of the terrorist attacks in Mumbai last month. Officials ordered army personnel on leave to report for duty and moved troops from Pakistan's border with Afghanistan and adjacent tribal areas, where they had been deployed to counter the Taliban and al-Qaeda insurgency. Some media reports suggested that as many as 20,000 Pakistani troops were redeployed. But a senior Pakistani security official, speaking on the condition of anonymity, said that the moves involved no more than 5,000 troops. "We are taking the minimum required defensive steps for our security in the face of Indian troops' escalation at the border," he said. "Reports of heavy redeployment of Pakistani forces are false." Pakistan and India, both nuclear-armed nations, have traded angry statements since India accused "elements" in Pakistan of planning the siege in Mumbai last month that left at least 170 people dead, including six Americans. Indian officials say the banned Pakistan-based group Lashkar-i-Taiba carried out the attacks and have demanded that Pakistan do more to stamp out such groups. Pakistan has denied any government role in the attacks. In New Delhi, government officials met to discuss Pakistan's reported troop buildup. Foreign Minister Pranab Mukherjee warned Pakistan against diverting its attention from fighting terrorism and called on its leaders to "bring to book the perpetrators of [the] Mumbai terrorist attack." "We would expect instead of raising war hysteria, they will address this problem," he said. Indian Prime Minister Manmohan Singh met with the chiefs of the army, navy and air force and later with his government colleagues to discuss security preparedness. The government also warned Indians against traveling to Pakistan. Pakistani Prime Minister Yousaf Raza Gillani said his country would avoid launching a military action but would retaliate with full force if attacked. "We will not take any action on our own. There will be no aggression from our side," he said. The United States urged the countries to cooperate in fighting terrorism. "We hope that both sides will avoid taking steps that will unnecessarily raise tensions during these already tense times," said White House spokesman Gordon Johndroe. The Pakistani security official said the additional troops were deployed near the cities of Kasur and Sialkot in Punjab province as well as the Line of Control, the de facto border dividing Kashmir, a region that has been claimed by both countries since the bloody partition of the subcontinent in 1947. The official said the troops were removed from areas where insurgents were inactive because of the snowy winter. Pakistan's chief military spokesman, Maj. Gen. Athar Abbas, could not be reached for comment on the reports. Maulvi Omar, a spokesman for the Pakistani Taliban, welcomed the government's decision to withdraw some troops from the tribal areas. "We will not attack the convoys of army withdrawing from tribal areas as it is a good development," he said, adding that the Taliban would help defend Pakistan against any aggression. In Dera Ismail Khan, a Pakistani city near the tribal area of South Waziristan, residents said they saw dozens of military trucks moving from the frontier area on their way to the Indian border. "I saw many trucks loaded with Pakistani soldiers moving from Waziristan early Friday morning," said Rahimullah, a shopkeeper in Dera Ismail Khan who was contacted by telephone. He said a soldier told him they were going to the Indian border.