Poland voted yesterday in a two-day referendum on joining the European Union in what would be the bloc's single biggest step across the old Cold War divide in its historic expansion eastward. Surveys suggest that three in four voters in Poland will vote to rejoin the West in the referendum ending today.

But apathy could keep turnout below the 50 per cent needed for the result to be binding in the largest of 10 countries invited to join the EU in May 2004.

Prime Minister Leszek Miller, whose minority cabinet's future depends on a strong 'Yes' in the vote, was among the first to cast a ballot yesterday.

About 25,000 polling stations opened at 6 a.m. First-day turnout figures will be released after they close at 8 p.m. and first exit polls are expected shortly after voting ends at 8 p.m. today.

Turnout below half of Poland's 29.5 million voters would force parliament to ratify EU entry by a two-thirds majority, shaking financial markets and Miller's unpopular government.

Prosperous city dwellers are the staunchest supporters of EU entry while poor farmers, workers of some nearly bankrupt state-owned enterprises and small retail traders tend to be euro-sceptic or apathetic.

Several influential Roman Catholic bishops cast "Yes" votes, echoing views of Polish-born Pope John Paul II, the highest moral authority in this religious nation.