AHMEDABAD, India (Reuters) - Police in communally sensitive Gujarat have detained at least 400 people to prevent Hindu-Muslim clashes during a Muslim day of mourning on Tuesday.

Riot police and paramilitary personnel have also been deployed in towns such as Ahmedabad, Surat and Baroda which have sizeable Muslim populations and a history of religious violence, a senior police officer said.

"Most of the detentions are in Ahmedabad. This is to check any kind of trouble normally triggered by anti-social elements," the officer said.

Gujarat was the scene of India's worst religious riots in a decade two years ago, when more than 1,000 people, mostly Muslims, were killed in a series of revenge attacks after a suspected Muslim mob torched a train, burning alive 59 Hindus.

Non-government groups put the death toll from the religious violence at over 2,500.

Muslim Shi'ites annually mark Muharram, a period of mourning to mark the martyrdom of the Prophet Mohammad's grandson Hussein more than 1,300 years ago.

Mourning reaches a climax on Ashura - the 10th day of Muharram - when some people flog themselves with steel-tipped flails or slash their bodies with knives in solidarity with Hussein. In India, Ashura falls on Tuesday.

Muharram marches in Gujarat have sometimes turned violent in the past when they passed through Hindu-dominated areas.

Police are not taking any chances this year after three people were killed last week in the industrial town of Baroda when Muslims and Hindus clashed over the route of a Muharram march.

"All precautions have been taken as we do with all festivals in Gujarat," said Deepak Swaroop, Gujarat's additional director general of police.