Describing media as the "conscience- keeper" of the nation, Prime Minister Manmohan Singh today asked it to keep away from sensationalism though it was "tempting" some times.

"The desire to be sensational should be avoided even though it is very tempting sometimes. Restraint should be exercised so that nothing that divides our society and country is written, broadcast or telecast", he said.

He prefaced his advice saying, "We are proud that freedom of expression is a Constitutional guarantee in India. Media in our country is not just a reliable barometer of public opinion; it is also the conscience-keeper of our nation."

In his address at the Golden Jubilee celebrations of Kerala Union of Working Journalists at the end of his two-day visit to the state, Singh said the country was going through difficult times and referred to the recent Assam violence and exodus of north-easterners from different states.

"Today our country is going through difficult times. The unfortunate incidents of the past few months have brought out worrying faultlines in our society", he said.

The tragic developments in Assam and their reverberations other places have shown that "We cannot afford to take social peace and harmony for granted", he said.

He emphasised the need to be constantly vigilant and work continuously towards promoting greater communal harmony and inter-group and inter-community dialogue.

In this task, the media has a very important role to play and its reporting and opinions should be "fair, objective and balanced", Singh added.

Earlier, laying the foundation for the Rs 5,180 crore Kochi Metro Rail project, Singh said the high speed of urbanisation posed unprecedented managerial and policy changes "that we must address and respond to with courage and determination."

Noting that an efficient transport system was "critical" for orderly growth of cities, he said the government has decided to support preparation of Detailed Project Reports for Metro rail in all 19 cities with over two million population.

The Prime Minister yesterday opened the three-day Emerging Kerala summit here aimed at wooing investors to the state.