According to Release International Buddhist monks are stopping Christians from using public cemeteries to make them feel unwelcome in their own country.
The charity says Buddhism is combining with nationalism which has led to an surge in persecution.
A growing number of persecution cases in Sri Lanka are now linked to local government officials, who have been closing churches and prayer meetings, the charity added.
A leading human rights lawyer, who did not want to be named for her safety, said there has been 120 cases of persecution since the middle of 2015.
Many other cases are going unreported, she added.
"In one case two Buddhist monks walked into a prayer meeting that a pastor was holding with some villagers.
"They shouted at him, they threatened him and when the pastor went to the police to lodge a complaint against them, the police officer said this is your fault, all of this is happening because of what you're doing."
She told of one occasion when a group of villagers gathered at a Christian burial: "They started shouting this is not a place they can bury Christians and they will not allow it.
"The villagers started surrounding the public cemetery and the police walked in and agreed with the mob.
"They said you can bury the Christians elsewhere, which was quite far away from their village".
Release International Chief Executive Paul Robinson said: "You don't normally associate Buddhism with violence, but time and again we hear that it is Buddhist monks who are leading the attacks against the churches. And our partners have found the monks are being aided by pro-Buddhist authorities.
"This has to be brought into the spotlight."