PARIS — The familiar sound of corks popping may soon be consigned to history as French wines start dropping the traditional cork for the screw cap.

While New World wines have been sealed with screw caps for years — with up to 90% of New Zealand wines and 60% of Australian bottles using them — the French have been far more reluctant to change their ways.

But according to one wine expert, two of the world’s top names — Domaine de la Romanée-Conti in Burgundy, whose bottles can sell for tens of thousands of pounds, and Bordeaux’s legendary Château Margaux — are now looking into screw caps.

Romanée-Conti would not comment on the issue, with screw caps still viewed as heresy by many purists. But the director general of Château Margaux, Paul Pontallier, confirmed that the Bordeaux domaine was trying them out.

“It’s true, we’ve been doing tests for the past four or five years,” he said. “But it’s too early to say whether we will use them, as our wines are made to be kept.”

However, one of Burgundy’s best-known producers, Jean-Claude Boisset, has already started using them on top wines, including a $200-a-bottle 2005 Chambertin grand cru. This year, a third of the producer’s 200,000 bottles will use screw caps.

“We started at the high end, because screw tops are perfect for fine wines that need to age, as they protect them better than cork from oxidation,” the head of bottling at Boisset, Gregory Patriat, said. “We’re not saying corks are bad; it’s just that screw tops are better.” The other alternative is a plastic stop, but wine growers say these are only of use on bottles to be drunk within two to three years, as they quickly change shape and let in oxygen.

“We had a lot of problems with cork stops in 2001,” the Laroche wine group’s Renaud Laroche said. “After that, we conducted lots of tastings and settled on screw tops. Entire batches of bottles [with corks] were defective. No car maker would accept one in 10 of its cars not working.” His group now uses screw caps on its highest-end wine, the Reserve de l’Obedience — a white chablis grand cru that sells for more than $120 a bottle.

However, he said that while white wines were perfectly suited to screw caps, as they maintained freshness, he still preferred cork for reds. “Its advantage remains to be proven for red wines to be kept,” he told Le Figaro newspaper.

Of the 7 billion wine bottles sealed each year, the number using screw caps has shot up from 300 million in 2003 to 2.5 billion this year. According to the world’s best-known wine critic, Robert Parker, bottles with corks will be in the minority by 2015. “The cork industry has not invested in techniques that will prevent … the musty, mouldy, wet-basement smell that ruins up to 15% of all wine bottles,” he wrote recently.

The one exception, he said, would be “great wines meant to age for 20 to 30 years that will still be primarily cork finished.”