Sri Lanka's main opposition the United National Party (UNP)'s headquarters on the outskirts of capital Colombo was the venue for a human rights exhibition highlighting the many people who have disappeared during the country's protracted conflict.
Dozens of supporters belonging to an extremist Buddhist organization Buddhist Power Force blockaded the headquarters resulting in an argument between those within the UNP building and the protestors.
The protestors stormed the headquarters alleging that the UNP was harboring "extremist elements" within the building.
Police managed to bring the altercation under control after several hours. Members of the Criminal Investigation Department ( CID) later arrested one person attending the exhibition under suspicion of having ties with the Tamil Tigers.
However the UNP insists that the detained individual was a family member of one of the people abducted during the conflict.
"Due to the repressive acts by the government the UNP has decided that we will not attend the opening ceremony of the Commonwealth Heads of Government Meeting (CHOGM) nor will we attend the sessions over the weekend," UNP Secretary General Tissa Attanayake told reporters.
UNP leader Ranil Wickremesinghe was expected to attend the CHOGM opening ceremony presided over by Prince Charles and Sri Lankan President Mahinda Rajapaksa.
Wickremesinghe's vehicle was also attacked by pro-government protestors on Wednesday as he attempted to visit the exhibition.
Sri Lanka has come under intense international pressure over its human rights record with Canadian, Indian and Mauritius Prime Ministers skipping CHOGM.
British Prime Minister David Cameron will travel to the country ' s war-torn north on Friday to observe the situation first hand.
Military and police turned back relatives of dozens of people who disappeared during the war who attempted to enter Colombo to stage a protest demanding credible investigation on Wednesday.
Sri Lanka ended a bloody three-decade conflict with Tamil Tiger rebels in 2009 but allegations of war crimes, failing to investigate into thousands of disappearances and lack of media freedom have grilled the regime of President Rajapaksa.
Xinhua
