New Delhi, Dec 19 (IANS): Terrorism that receives support from outside the country from state and non-state actors inimical to India needs to be fought, President Pranab Mukherjee said Thursday, noting also the threats posed by changing technology.

The president said state and non-state actors were engaged in efforts to destabilise the country.

"We have to fight against terrorism that receives support from outside our country. Both state and non-state actors inimical to the nation are continuously engaged in efforts to destabilise India," he said, delivering the annual Intelligence Bureau Centenary Endowment lecture at Vigyan Bhavan.

"The challenges to our security can come from many sources," he said.

Left-wing extremism is another serious threat to social peace and harmony in India, the president said.

"Rapid change in technology has also resulted in new threats," the president said, adding: "The misuse of the social media is now a weapon that terrorists across the world and anti-nationals are employing with greater sophistication."

"This has to be combated (through) adopting superior tactics and technology," he said.

The security system needs to be geared up for new challenges, the president said.

"As new challenges emerge, we would also need to upgrade our skills and technological capabilities. For security personnel to effectively counter these threats, timely and reliable intelligence is of utmost value," he said.