Jimmy Carter and two other former world leaders who are part of a group known as “The Elders” wrapped up a visit to Myanmar on Thursday with calls to address spiralling Buddhist-led violence against minority Muslims.

“No one can afford to ignore these senseless, destructive, repeated acts of brutality,” the group said in a press release.

“This is a very serious problem for the world community,” the former U.S. President said, adding how it is tackled by the new quasi-civilian government will be a “key test as to whether Myanmar is going to honour international standards of human rights.”

They also praised Myanmar’s transition from a half-century of military dictatorship to a budding democracy, pointing to the release of thousands of political prisoners, ceasefire agreements with many of the country’s armed ethnic groups and an end to censorship.

They said it was “remarkable” how far the country had come in just two years.

At least 240 people have been killed and other 140,000 forced to flee their homes, most of them Muslims.

“Myanmar still has a long way to go,” said Mr. Carter. He was joined on the trip by Finland’s former President Martti Ahtisaari and Norway’s former Prime Minister Gro Harlem Brundtland.

“It could take decades to overcome the ingrained prejudices promoted by extremist voices in parts of the country,” the Elders said in their statement. “This will require far-reaching cultural changes in all parts of society, including through changes in the education curriculum.”

They held private meetings with President Thein Sein and other high-level governmental officials, legislators, religious leaders and civil society groups.

Nelson Mandela founded the 13-member group known as “The Elders” in 2007 to work toward peace and human rights.