He joined as Assistant Scientific Adviser in the Human Resource Development Programme of the Ministry of Science and Technology in the Government of Pakistan in 1985.

UNESCO: Education

As Mr Obama's top counter-terrorism adviser, Mr Brennan helped oversee the drone programme.

BBC: John Brennan confirmed as CIA head after filibuster

The main conference is due to open in Londonderry on Monday, where delegates will be addressed by Phil Wood, a key adviser to the Council of Europe's Intercultural Cities programme.

BBC: Peace wall in Belfast