DUBLIN — Europe’s effort to crack down on tax havens gained momentum during the weekend as the number of countries agreeing to share more bank information doubled.

Miroslav Kalousek, the Czech finance minister, pledged to join the push for more automatic exchanges of bank records that already had the backing of Britain, France, Germany, Italy and Spain, a spokesman for the Czech representation to the European Union said Sunday.

The spokesman said the Czech minister made his overture on Saturday during a two-day meeting of European finance ministers where Poland, followed by Belgium, the Netherlands and Romania, also signed up, bringing the number of countries supporting the initiative to 10. The campaign is being strongly backed by the French finance minister, Pierre Moscovici.

For France, the issue has taken on greater urgency since Jérôme Cahuzac resigned as budget minister after acknowledging he had foreign holdings in Switzerland that he had previously denied.