Former diplomat Dayan Jayatilleke has been appointed the International Relations Advisor to Opposition Leader Sajith Premadasa.

Jayatilleke, formerly a supporter of Mahinda Rajapaksa, extended his support to Sajith Premadasa when the latter became the presidential candidate of the UNP-led alliance.

He served as an advisor Sajith Premadasa'sfather, former President Ranasinghe Premadasa from 1989 to 1993.

He was also the Director of Conflict Studies at the Institute of Policy Studies (1990–94) and the Executive Director of the Premadasa Centre (1994-2000). He was also editor of Lanka Guardian, the journal founded by his father, from 1996 to 1998

Jayatilleka received a M.Phil. degree from the University of Colombo in October 2002. He was visiting senior fellow and adjunct professor at the Johns Hopkins University between 2005 and 2006.He was later appointed senior lecturer at the University of Colombo. He was a member of the Council of Management of the Bandaranaike Centre for International Studies (BCIS). He received a PhD degree from the Griffith University in 2007 after writing a thesis titled The Moral Sierra Maestra: The Moral-Ethical Dimension of the Political Thought of Fidel Castro.