Zagreb - Croatia will definitely not hold a referendum on its membership in NATO as opponents of the alliance have failed to gain enough support to force a vote on the issue, reports said Monday.

Over the past two weeks some 40 non-governmental organizations were able to collect only a third of the 450,000 votes they needed to push through a motion for a referendum.

They blamed shortage of funds to campaign, along with what they describe as conditions restrictive to civic initiatives.

The organizers would still pass the petition to parliament and launch a public debate on conditions effectively disallowing civic motions for a referendum, the reports said.

NATO invited Croatia to join at its early-April summit in Bucharest. Roughly two out of every three Croats supports their country's pending membership of the alliance at that time.

NATO's popularity however jumped from slightly above 50 per cent in just one month, owing to a strong campaign by Prime Minister Ivo Sanader's government and NATO as much as because of re-emerging tension in the Balkans following the secession of Kosovo from Serbia.