A Thai justice ministry official says at least 78 people died during a riot Monday in southern Thailand as security forces clashed with Muslim demonstrators.

The official (Manit Suthaporn) says the victims appeared to have died from suffocation in the crush outside a police station in Narathiwat province.

Officials say more than 1,000 people were arrested during the riot, and authorities ordered a curfew in three predominantly Muslim southern provinces.

The protesters were demanding the release of six security guards accused of giving their weapons to militants.

Thai Prime Minister Thaksin Shinawatra said the security crackdown was justified, accusing the demonstrators of trying to cause trouble.

More than 300 people have been killed by violence in southern Thailand since January. Thai officials blame most of the activity on Muslim separatists.