Eighteen Indian policemen were killed today when their truck was blown up by a landmine placed under a culvert by Maoist rebels in the east of the country, police said.
The attack took place at Chakia, 100 km (62 miles) east of the holy Hindu town of Varanasi in the populous Uttar Pradesh state.
Police had said initially 15 policemen were killed and five seriously wounded in the blast but a police spokesman said later on Saturday that seven policemen were critically hurt and three of them died in hospital. "The toll could go up as two of the wounded are in a very critical state," the spokesman said.
The blast took place near the border with the neighbouring state of Bihar where Maoist guerrillas, fighting for the rights of landless labourers and poor peasants, have a strong presence.
Police reinforcements had been sent to Chakia, located in a sparsely-inhabited region with a rocky undulating landscape, and were scouring the area.
Maoist rebels operate in southern and eastern India and often attack the police through ambushes and landmines. They are also active in Nepal, which borders both Uttar Pradesh and Bihar.
Intelligence agencies say they are worried by reports of cooperation between Indian and Nepali Maoist insurgents and greater unity among India's several Maoist guerrilla groups.