In the wake of the controversy over the visit of nuclear-powered US aircraft carrier USS Nimitz to Chennai, Prime Minister Manmohan Singh [Images] on Wednesday dismissed apprehensions, saying the warship does not carry nuclear warheads.

Dr Singh said there was nothing wrong in a warship visiting Indian ports.

The warship does not carry nuclear warheads, he told reporters on the sidelines of a book release function at his residence when referred to the mounting attack on the government for allowing Nimitz to call at Chennai port later this week.

The United Progressive Alliance government's Left allies and former Tamil Nadu chief minister Jayalalithaa have been the most vocal critics of the US Navy carrier's visit.

With fears being raked up of radiation hazards from Nimitz, the government on Wednesday said a "stringent radiation monitoring protocol" is in place for the warship's visit to Chennai.

"A standing environmental safety committee has carried out a detailed survey of the Chennai port and cleared the anchorage of USS Nimitz from radition hazard point of view," a defence ministry spokesman said in Delhi.

Noting that a radition safety contingency plan is in place, spokesman Sithansu Kar said experts from the Bhabha Atomic Research Centre and the Defence Research and Development Organisation have set up radiation monitoring laboratories on ships for frequent monitoring of water and air samples during the course of the three-day visit of the warship.