* Some landslide, flood areas are not accessible-officials

AGALAWATTE, Sri Lanka, May 29 (Reuters) - Floods and landslides in tropical Sri Lanka have killed at least 164 people, authorities said on Monday, as a cyclone grew in the Bay of Bengal, churning towards Bangladesh and forecast to bring torrential rains to neighbouring India. The floods have reached roof level and cut off access to many rural Sri Lankan villages, disrupting life for half a million people, many of them workers on rubber plantations, officials said. Villagers in Agalawatte, in a key rubber-growing area 74 km (46 miles) south-east of the capital, Colombo, said they were losing hope of water levels falling soon after the heaviest rain since 2003. Fifty-three villagers were killed and 58 were missing. "All access to our village is cut off. A landslide took place inside the village and several houses are buried," Mohomed Abdulla, 46, told Reuters. The Sri Lankan military has sent in helicopters and boats in rescue efforts in the most widespread disaster since the 2004 Boxing Day tsunami. About 100 people were missing in total. The meteorology department said a depression in the Bay of Bengal had intensified into what has been named Cyclone Mora and forecast torrential rains over the next 36 hours. Residents in seven densely populated districts in the south and centre of Sri Lanka were asked to move away from unstable slopes in the case of further landslides. The wettest time of the year in Sri Lanka's south is usually during the southern monsoon, from May to September. India warned of heavy rains in the northeastern states of Tripura, Mizoram, Manipur, Nagaland and Arunachal Pradesh as Cyclone Mora moved further up the Bay of Bengal. Reuters witnessed some people stranded on the upper floors of their homes. Civilians and relief officials in boats distributed food, water and other relief items. One of the worst-hit areas was the southern coastal district of Matara which is home to black tea plantations. Rohan Pethiyagod, head of the Tea Board in the world`s largest exporter of top quality teas, said supplies would be disrupted for the next tea auction because of lack of transportation. Sri Lanka has already appealed for international assistance from the United Nations and neighbouring countries. Some areas in the southern coastal district of Galle, popular with foreign tourists, have not received relief materials due to lack of access. "My entire village is cut off and nobody can come to this village," C.M. Chandrapla, 54, told Reuters over the phone from the tourist village of Neluwa. "There have been no supplies for the past two days. Water has gone above three-storey buildings and people survive by running on to higher ground."
More than 300,000 people are evacuated in Bangladesh as Cyclone Mora approaches.