The convention, organised by hardline Bodu Bala Sena (BBS) or Forces of Buddhist Power, is already facing opposition from minority Muslims, who constitute 7 per cent of Sri Lanka's population.
The BBS, which has been accused of instigating hate attacks on the island, said Mandalay-based monk Ashin Wirathu would be an honoured guest at the convention.
Wirathu, the spiritual leader of an anti-Muslim movement in Myanmar, was today received at the international airport by top BBS officials, according to the website of the group.
The Sri Lanka Muslim Council had written to President Mahinda Rajapaksa urging him deny visa to Wirathu to visit the country.
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"The presence of such a person who has caused so much violence on the Burmese Muslims would be a real threat to peace and peaceful co-existence in Sri Lanka," ColomboPage quoted the Council as having said in the letter.
The BBS has been accused of instigating a string of attacks against mosques, Christian churches and Muslim-owned businesses. It is accused of harbouring a campaign against the island's Muslim minority.
Sri Lanka and Myanmar share a common Buddhist heritage and have close cultural ties.
In Myanmar, Buddhist-Muslim clashes have left at least 250 people dead and tens of thousands displaced since fighting broke out in Myanmar's western state of Rakhine in 2012.