May 23 (Reuters) - The United Nations' aviation agency said on Sunday it was "strongly concerned" over the apparent forced landing of a Ryanair jetliner in Belarus.

The International Civil Aviation Organization said in a Twitter post that the incident may have contravened the Chicago Convention, a 1944 treaty designed to promote the peaceful use of civil aviation, which is managed through the Montreal agency. (Reporting by Tim Hepher; Editing by Alexander Smith)