Islamabad ( CNN ) -- A convoy of more than 100 vehicles left Islamabad , Pakistan , on Saturday on a march toward South Waziristan to protest U.S. drone attacks . Pakistani cricketer-turned-politician Imran Khan is leading the march , which includes about 35 members of the U.S. anti-war group Code Pink . The group traveled to Pakistan last week to join the march , group representative Mirza Shahzad Akbar told CNN . `` We are here to say , on behalf of those Americans with a conscience , that we apologize to the people of Pakistan for the killing and suffering , '' Medea Benjamin , a founder of Code Pink , said at a news conference Thursday . American activists in Pakistan to protest U.S. drone strikes . The U.K. advocacy group Reprieve and former Prime Minister Tony Blair 's sister-in-law , Lauren Booth , are also part of the convoy . But senior government officials warn that the participants will not be allowed into South Waziristan . Opinion : A dangerous new world of drones . `` We have already informed the convoy that we will not allow the participants to enter due to security reasons , '' Shahid Ullah , a senior government official , said . `` The situation in the tribal areas is comparatively good but not suitable for any gathering there , '' Tashfeen Khan , another government official , said . `` Visiting South Waziristan with foreigners would not be advisable . It can create problems , '' he said . While the government has given no assurances for the safety of the march , the Pakistani Taliban has also voiced concern at the convoy entering the volatile region . `` We have n't given any kind of guarantee for the safety of the so-called Peace March planned to visit South Waziristan , '' said Ihsanullah Ihsan , spokesman for the Pakistani Taliban . Opinion : The folly of drone attacks and U.S. strategy . The counterterrorism drone strike program in Pakistan has long been controversial , with conflicting reports on its impact from the U.S. government , Pakistani officials and independent organizations . American officials insist that the choice and execution of the strikes -- begun under President George W. Bush and ramped up under President Barack Obama -- meet strict standards and that cases of civilian deaths or injuries are extremely rare . But a study released last month by Stanford Law School and New York University 's School of Law said the drone attacks have killed far more people than the United States acknowledges , traumatized innocent residents and been largely ineffective . Civilians account for a significant portion of those killed , the study said . Meanwhile , fliers were distributed in the city of Tank on Friday from a militant splinter group claiming that Imran Khan was a Jewish American agent and that he would be endangering his own life and those who were traveling with him if he entered the tribal areas . Convoy participants hope to reach South Waziristan on Sunday and hold a demonstration against drone attacks in northwest Pakistan . Journalists Amir Iqbal and Nasir Habib contributed to this report .
More than 100 vehicles left Pakistan 's capital Islamabad to protest drone strikes . The protesters were demanding an end to the US drone attacks in Pakistan's tribal areas and a halt on CIA flights over Pakistani territory. American officials insist drone strikes meet strict standards .