A Pakistani tribesperson is pictured along a shuttered market in Miranshah in North Waziristan, a stronghold for Taliban and Al Qaeda-linked militants near the border with Afghanistan on June 15, 2014 during a curfew imposed by authorities

The Pakistani Taliban on Monday warned foreign firms to leave the country and vowed retaliatory strikes against the government after thousands of troops launched a long-awaited offensive in a troubled tribal district.The statement came as Pakistan's major cities braced for a backlash by deploying thousands of soldiers and paramilitaries while placing hospitals on high alert for incoming casualties.The offensive on North Waziristan, a stronghold of Taliban and Al Qaeda militants, was launched a week after a brazen insurgent attack on Pakistan's main airport in Karachi which left dozens dead and marked the end of a troubled peace process."We warn all foreign investors, airlines and multinational corporations that they should immediately suspend their ongoing matters with Pakistan and prepare to leave Pakistan, otherwise they will be responsible for their own loss," spokesman Shahidullah Shahid said in a statement."This thing is clear to all that the capital gained (by Pakistan) through your activities and trade falls on innocent tribal women and children like fire and iron," he added.The Islamist group also vowed to take revenge on the government."We hold Nawaz Sharif's government and the Punjabi establishment responsible for the loss of tribal Muslims' life and property as a result of this operation," the statement said."The retaliatory actions of the Mujahedeen will make you a cautionary tale in history."Shahid added the Taliban would "burn your palaces in Islamabad and Lahore" referring to the capital city and Sharif's hometown from where he derives his support base."Remember that you will once again crave for negotiations and peace, but then it would be too late," he added.The warning came as major cities beefed up their security, as troops were seen patrolling the streets of Islamabad, Lahore and Karachi."The security of the capital was already on alert, but a new alert had been issued," an Islamabad police spokesman told AFP."Some 3,000 policemen have been deployed in Islamabad on security duties and patrolling has been increased," he said, adding that troops and paramilitary rangers had also joined them, without giving any figure.

Police in Pakistan's economic hub Karachi have declared a "Red Alert" and cancelled leave for all 27,000 personnel, spokesman Atiq Shaikh told AFP.In northwestern Khyber-Pakhtunkhwa province which borders the tribal zone, the government has declared a state of emergency in all hospitals and asked them to prepare for incoming casualties, provincial health minister Shahram Khan Tarakai said in a statement.