An overcrowded river ferry broke in two and sank in northeast India during a severe storm on Monday, leaving at least 105 people dead and almost as many missing, police said.

As rescuers struggled in heavy rain to find survivors weeping relatives lined the shores of the fast-flowing Brahmaputra river in Assam state, desperate for news of family members on board the vessel.

It was carrying around 350 men, women and children and police said some 150 people were rescued or swam to safety after the accident, which occurred as torrential pre-monsoon rains lashed the region.

The death toll could make the ferry sinking one of the worst in recent memory in South Asia, where such disasters are common due to lax safety standards and overloading.

"A storm split the steamer into two," Assam state police chief J.N.

Choudhury told AFP.

"Rescue workers along with villagers have recovered about 105 bodies from the shores of the river," said P.C. Haloi, police chief of Dhubri district, from where the boat set out. "The fate of around 100 others is not known."

The overcrowded double-decker ferry had no lifebelts and Rahul Karmakar, who witnessed the sinking, told AFP: "I could see people being swept away as the river current was very strong."

He added that "chances of survival seem to be remote" in the river, swollen by the heavy storm.

Rescuers struggled to find survivors but their efforts were hampered by high winds, torrential rains and darkness.

Local fishermen, who live with their families in tiny hamlets stretching along the Brahmaputra -- which has a reputation as a treacherous, turbulent waterway -- combed the shores for survivors as night fell.

"The weather is very bad there. It is making the rescue efforts very difficult," state Transport Minister Chandan Brahma told AFP in Assam's main commercial city Guwahati.

Strong winds had uprooted trees, blocking roads leading to the disaster site and preventing some rescue teams from reaching the area, said officials.

More rain was forecast for the area on Tuesday.

The bodies of the victims were being kept at a local hospital.

The boat was on its way from Dhubri, some 300 kilometers from Guwahati, to Fakirganj.

Prime Minister Manmohan Singh called the sinking a "tragedy".

He was "shocked and grieved to know about the loss of lives", he said in a statement, adding he had given instructions "for all possible assistance to the government of Assam in relief operations".

Assam state chief minister Tarun Gogoi said Singh had promised to rush disaster response units from New Delhi and other locations.

"Army, Border Security Force and other rescue teams with mechanized boats have moved to the site but nightfall and bad weather are hampering rescue efforts," Gogoi told AFP.

In one of the last major ferry disasters in India, at least 79 Muslim pilgrims drowned when an overcrowded boat carrying 150 people sank in the eastern state of West Bengal in October 2010.

In March this year, some 138 people died in neighboring Bangladesh when an overloaded ferry carrying 200 people sank in the Meghna river southeast of the capital Dhaka. (AFP)