The Elders, a group of prominent former world leaders, voiced concern on Thursday at U.S. President Donald Trump's refusal to concede electoral defeat, saying it showed disrespect for the integrity of American democracy.

The group was founded by late former South African President Nelson Mandela and is now chaired by former Irish President Mary Robinson.

It includes Mandela's widow Graca Machel, former U.N. Secretary-General Ban ki-moon, Nobel Peace Prize-winning former presidents of Colombia and Liberia, and an array of other former world leaders. Former U.S. President Jimmy Carter is an emeritus member.

Trump's position was "putting at risk the functioning of American democracy," the group said, calling for him to accept the verdict of the ballot box.

Trump has focused on efforts to overturn the Nov. 3 election's results in closely contested states, claiming evidence of irregularities that could affect the outcome, despite skeptical reception from judges.

"The continued assertions of electoral fraud by the President and some senior members of the Administration and of the Republican Party, offered as yet without any compelling evidence, convey a lack of respect for the integrity and independence of the democratic and legal institutions of the United States," the Elders said in a statement.

"Those who stand to benefit from the current impasse are autocratic rulers and malign actors who wish to undermine democracy and the rule of law across the world."

Robinson, who served as U.N. human rights chief, noted that The Elders had previously commented on "volatile and undemocratic situations in states such as Kenya, Sri Lanka, and Zimbabwe."