Former President Jimmy Carter has taken leave of election observation efforts in South America amid health concerns, the Carter Center announced Sunday.

Specific details about the 90-year-old native Georgian’s condition were not provided.

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

The election in Guyana, scheduled for Monday, will be the 100th observed around the world by the Carter Center, a not-for-profit, non-governmental organization based in Atlanta. Through its election observations, the center works to “advance democratic elections and governance consistent with universal human rights,” according to its website.

“President Carter is hopeful about Guyana’s election,” the Carter Center’s statement said, “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.”

No further information was provided.