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 Buddhist-led violence against minority Muslims and end impunity for the perpetrators.

"No one can afford to ignore these senseless, destructive, repeated acts of brutality," they said.

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

The three visiting Elders — Carter, who was president from 1977 to 1981, former Finnish President Martti Ahtisaari, and former Norwegian Prime Minister Gro Harlem Brundtland — called for an end to impunity and for freedom of religion.

Carter praised Myanmar's transition from a half-century of military dictatorship to a budding democracy, pointing to the release of thousands of political prisoners, cease-fire agreements with many of the country's armed ethnic groups and an end to censorship, saying it was remarkable how far the country had come in just two years.

But, he added, it "still has a long way to go."

Newfound freedoms of expression have exposed deep-seated hatred in the predominantly Buddhist nation of 60 million, initially against ethnic minority Muslims known as Rohingyas, and then to Muslims in general, leading to some of the worst sectarian violence the country has seen in decades.

At least 240 people have been killed and another 140,000 forced to flee their homes, most of them Muslims. Many of those responsible for the worst of the bloodshed remain unpunished.

In many cases, security forces stood by as Buddhist mobs chased down their victims with machetes, wooden sticks and iron chains.

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

They met with President Thein Sein and other officials, legislators, religious leaders and private groups.

Former South African President Nelson Mandela founded the 13-member group known as "The Elders" in 2007 to work toward peace and human rights.