Thousands of supporters of the group attended a rally in Maharagama to hear the speeches by the group’s monks.
The Bodu Bala Sena, or Buddhist Strength Force, also said foreign propagators of religions should leave the country within a month. The calls come at a time of mounting religious tension in the country.
President Mahinda Rajapakse has called on monks not to incite religious hatred and violence.
The group’s secretary-general, Venerable Galaboda Aththe Gnanasara, told the crowds that “only monks can save this race”, referring to Sinhalese.
He claimed that Christian and Muslim extremists were threatening Buddhists, and said hundreds of monks were ready to fight. “Our country is a Sinhalese one and we are its unofficial police,” he said.
The group has denied being anti-minority, and has dissociated itself from the recent attacks on Muslim and Christian targets.
But one member of the group, Dilanthe Withanage, accused “some” unnamed countries of “funding Christian fundamentalists as well as Muslim fundamentalists” in Sri Lanka.
The leaders called for a boycott of halal meat and demanded shops clear their stocks by April
Meanwhile Charles Haviland of BBC News told that the BBC team and driver were seriously threatened with violence by some members of a mob of more than 20 young men.
“Some police arrived and looked on as my Sri Lankan colleagues were verbally abused in filthy language, described as “traitors” and accused of having “foreign parents” and working for a “foreign conspirator” who was “against Sri Lanka”.