The incident occurred in Kandhamal district, central Orissa, police said, one of several states where armed Maoist rebels have waged a decades-long battle to overthrow state and national authorities.

"Maoists have abducted two Italian nationals from Daringbadi area of Kandhamal district," regional deputy inspector general Radha Krishna Sharma told AFP.

Sharma said the Maoists had initially nabbed four people on Saturday, including two Indians. They released the Indian hostages on Sunday morning. A search is underway to locate the two remaining hostages.

According to Indian news channel NDTV, the tourists were kidnapped while taking photographs of local women bathing in a river.

Local television reports said the kidnappers had issued a set of 13 demands for the release of the Italians, asking police to release an unspecified number of prisoners and end their operations to root out Maoists from the region.

The Indian government has described the Maoist movement, which often targets police and soldiers with deadly roadside mine ambushes, as the country's biggest internal security threat.

The insurgency, which began in 1967, feeds off land disputes, police brutality and corruption, and is strongest in the poorest and most deprived areas of India, many of which are rich in natural resources.

The rebels say they are fighting for the rights of neglected tribal people and landless farmers and their ultimate goal is to capture India's cities and overthrow parliament.

They have kidnapped government officials and police officers in the past to raise ransom payments and negotiate other demands.