Only 10 years ago Poland's western borders marked the impassable limit of the Warsaw Pact - the Iron Curtain. Its eastern borders were little more than checkpoints. On accession to the EU it is the eastern 1,761km frontier which will be sealed to become the EU's external border, while the western one will all but vanish.

Poland's participation both in the Union and the Schengen Treaty on passport-free travel, now being incorporated into the EU treaty, will impose huge new obligations on the state to control access to the entire Union.

A major part of the border control apparatus is thus being shifted across the country, new fences are being built, new technology is being brought in to link Poland to the Schengen information system, visa rules and regulations are being harmonised, customs being trained to watch for smugglers of goods, drugs and people, and the police are learning to co-ordinate their drive against organised crime with their EU counterparts.

It's by no means cheap but it's also controversial. Last December Poland imposed a visa requirement for the first time on Belarus, Ukrainian and Russian citizens in the name of harmonisation with the EU.

The move largely put a finish to a lucrative small traders' black market from Ukraine and Belarus and provoked protests from many Poles who insisted that the country should not sacrifice its historic ties with them.

Maciej Lewandowski, the deputy director of the European integration section of the Ministry of the Interior, defends the move. Rather now, gradually, he says, in a framework of co-operation than leaving such changes to a "spectacular" last minute closing of borders on the day of Polish accession.

But he insists that the new visa regime will not impede the development of the traditional cultural and trade ties across these borders, insisting as many here do, that Poland's connections in eastern Europe can provide the catalyst for a new relationship for all of the Union with the former Soviet bloc states.

Ironically, however, while they are willingly working to reinforce a new border regime to the east to protect the Union from unwanted visitors, some in the EU are insisting that Polish workers will have to be kept out of the EU's labour markets.

The Germans, backed by the Austrians, have even suggested a 10-year post-accession transition period before the Union's free movement of labour provisions click in fully.

It is a proposal that plays very badly with the Polish electorate, smacking of second-class membership. The Prime Minister, Jerzy Buzek, says that Poland's opening negotiating position is for immediate full access to the labour market. He insists that fears of a flood of migrants reflects a profound underestimation of the extent of their success in making the economy one which people will not wish to flee from.

Lewandowski agrees, pointing to the fact that precisely the same fears were raised ahead of an agreement in 1996 to dispense with the need for visas for Polish visitors to the EU. The unchecked and quite "manageable" flow of Polish workers into the EU's black economy has not been such as to justify such concerns. Nor did Spanish and Portuguese accession have such dramatic consequences.

Poland's ambassador to the EU, Jan Truszczynski, acknowledges the issue is going to be a problem and probably "one of the last issues to be dealt with in the final package deal". Although opposed to a transitional period he says he "cannot rule out that by way of give and take at the negotiating table we might be forced to, or indeed ourselves be inclined to, exchange a transitional period on free movement of labour for a transitional period on something else".

But he warns the Union should not forget that accession will be submitted to a referendum - the result "is not a forgone conclusion". Free movement is regarded by Poles as something very high on their priorities - "not as an economic issue but a question of equal treatment", he says.

And one point of contention where a trade-off might with this issue might be possible is that of the Polish legal requirement for significant land purchases to be authorised by the state.

Fears that rich German farmers will buy up once politically contested Polish land make conforming to basic single market regulations difficult. Lewandowski argues that the Union must understand their predicament: although permission is rarely refused, a combination of deep historical resonances and a sense of unfairness at the disparity between the economic power of German farmers and their counterparts make it difficult to concede in the short term.