Amnesty International called on Canadian authorities to arrest and prosecute George W. Bush, saying the former U.S. president authorized “torture” when he directed the U.S.-led war on terror, AFP reports.

Bush is expected to attend an economic summit in Surrey in Canada’s westernmost British Columbia province on October 20.

The London-based group charged that Bush has legal responsibility for a series of human rights violations in a memorandum submitted last month to Canada’s attorney general but only now released to the media.

“Canada is required by its international obligations to arrest and prosecute former president Bush given his responsibility for crimes under international law including torture,” Amnesty’s Susan Lee said in a statement.

“As the U.S. authorities have, so far, failed to bring former president Bush to justice, the international community must step in. A failure by Canada to take action during his visit would violate the UN Convention Against Torture and demonstrate contempt for fundamental human rights,” Lee said.

A spokesman for the Canadian government was not immediately available for comment.

Bush cancelled a visit to Switzerland in February, after facing similar public calls for his arrest.

Alex Neve, secretary general of Amnesty International’s Canadian branch, told a press conference the rights group will pursue its case against the former U.S. president with the governments of other countries he might visit.

Amnesty, backed by the International Civil Liberties Monitoring Group, claims Bush authorized the use of “enhanced interrogation techniques” and “waterboarding” on detainees held in secret by the Central Intelligence Agency between 2002 and 2009.

The detention program included “torture and other cruel, inhuman and degrading treatment [such as being forced to stay for hours in painful positions and sleep deprivation], and enforced disappearances,” it alleged.