DMK President M Karunanidhi today alleged that Sri Lankan police had prevented hundreds of Tamil protesters from leaving northern Vavuniya town to take part in a rally at Colombo and said such "autocratic" activities by the island government were condemnable.

Karunanidhi recalled that the US Embassy in Sri Lanka had asked Colombo to allow free movement of citizens.

"These family members are calling for information about their missing loved ones. The Embassy calls upon Sri Lankan authorities to allow free movement of these citizens. The right to freely express opinions is universal and protected under Sri Lankan and international law," the US Embassy had said on Wednesday.

The DMK chief said in a statement that the people had planned to take out a rally in Colombo pressing for demands including finding out missing Tamils and releasing those lodged in jails as prisoners of war.

Police had allegedly created hurdles to prevent them from proceeding to Colombo and due to the 'anti-democratic' activity, people staged the protest at Vavuniya itself, he said.

"It is condemnable that Sri Lankan government is denying basic democratic rights and is constantly involved in such autocratic activities," he said.

Karunanidhi later told reporters that his party MPs had staged a walk out in the Lok Sabha as the Minister's reply was "not convincing".

To a question, the DMK president said he will discuss with the party MPs the future course of action over this matter in Parliament.