Georgetown (Guyana) (AFP) - Former US President Jimmy Carter on Sunday cancelled plans to observe general elections in the South American country of Guyana after falling ill, his organization said.

The 90-year-old Carter left the country for the city of Atlanta in his home state of Georgia, The Carter Center said.

The nature of his illness was not disclosed.

"President Carter was not feeling well and has departed Guyana to return to Atlanta today. The Carter Center election observation mission in Guyana is continuing its work and will keep him informed of developments," a statement read.

Carter was the 39th president of the US and held office between 1977 and 1981. He remains very active in global human rights work.

Prior to leaving the former British colony, Carter held separate talks with the leader of Guyana's main opposition coalition and the country's president, Donald Ramotar.

Forty-nine other observers are remaining in Guyana to observe Monday's poll, which is expected to be keenly contested between the country's two major political parties.

President Carter is hopeful about Guyana's election and expressed his commitment and that of The Carter Center to supporting Guyana in the days ahead, stressing the need for a peaceful process before, during, and after the election, the center said.