US President George W Bush said Monday his main anti-terrorism adviser is resigning, the latest top aide to depart as he heads toward the last year of his presidency, according to DPA. Frances Townsend, 45, will give up the post of Bush's assistant for homeland security and counterterrorism early next year after more than four years on the job, the White House said. She "has ably guided" the president's council of homeland security advisers, playing an integral role in setting the US administration's anti-terror policies after the September 11, 2001 attacks, Bush said in a statement. Named by Bush to the White House job in June 2003, Townsend also coordinated policies with US allies. White House spokeswoman Dana Perino indicated that Townsend, a former prosecutor, will take a private-sector job. No successor was immediately announced.