New Delhi, Mar 20 (IANS): Prime Minister Manmohan Singh Tuesday said the abduction of two Italian nationals in Odisha is a "grim reminder" of the challenge posed by Maoists to India's internal security.

"The abduction of two foreign nationals recently is a grim reminder to all of us of the challenge to our internal security from leftwing extremism," the prime minister said in the Rajya Sabha in his reply to the motion of thanks on the president's address.

Italian nationals Bosusco Paolo and Claudio Colangelo were abducted March 14 when they were on a trek in Odisha's Kandhamal district. The two Italians were based in Puri.

Maoists claimed the tourists were kidnapped after they were found taking "objectionable" photographs of some tribal women near a rivulet. They demanded, among others, that the government stop its anti-Maoist combing operations.

The prime minister also asked the people of the country to be "careful and alert" if threats from Maoists and terrorism were to be weeded out.

He said the government was committed to dealing with terrorism.