NATO on Tuesday denied allegations that its naval vessels failed to help a drifting boat with Libyan migrants aboard, leaving 61 of them dead.

"NATO has reviewed all relevant information available...We can find no evidence whatsoever of any NATO ships been involved in this tragic incidence reported by the Guardian," NATO deputy spokeswoman Carmen Romero told a press briefing at NATO headquarters.

"Ships under NATO command will always respond to calls from ships in distress. This is the duty under the law of the sea and suggesting our ships' captains will do otherwise is unfair and is disrespectful," she said.

The Guardian newspaper reported that a boat carrying 72 migrants ran into trouble in late March after leaving Tripoli for the Italian island of Lampedusa.

Sixty-one migrants were left to die in the Mediterranean after a number of European military units apparently ignored their cries for help, the Guardian said. Two of the nine survivors claim this included a NATO ship.

A senior NATO official, Brigadier General Claudio Gabellini, said from Naples via video conference that if NATO ships got involved in such events, captains would "do everything in their power to ensure that their behavior is according to the international maritime laws and traditions."

International maritime law requires all vessels, including military units, that spot a vessel in distress must offer help where possible.