UK officials argued for a transitional period before the EU's highest court be allowed to have jurisdiction over police and judicial cooperation in criminal matters.

The current situation means that member states can choose whether the European Commission and the European Court of Justice may check compliance with EU law in this area - 15 of the 27 member states have agreed to give this power to the court.

The rejected EU constitution changed the status quo to allow the court to have jurisdiction, something that many member states wanted carried over into the new Reform Treaty that adopts several of the constitution's innovations.

However, London is now arguing for the court not to be given this power - which ultimately means that the EU decides whether a member state is complying with a given law as well as defining the extent to which it should comply - for some years.

London is asking that the court's power "does not kick in immediately," said an official who noted that London's position had "not gone down wonderfully."

Contradiction

The official also said that London's position was regarded as "somewhat of a contradiction" given its call for member states to implement anti-terrorism laws after the London bombs in July 2005.

At the moment getting anti-terror legislation in place throughout the EU is tortorously slow. The EU arrest warrant - heralded as key to the bloc's anti-terror fight - was hampered by delays and incorrect implementation even though it was meant to be fully in place in 2004.

Several member states - including Belgium and Spain - are annoyed by London's treaty stance, with Britain already seen as having received its fair share of concessions by not having to participate in this area if it chooses not to, as well as another opt-out from the charter outlining EU citizens' rights.

Speaking on the ongoing talks, senior Polish MEP Jacek Saryusz-Wolski noted that for the UK, "the most serious question is on justice and home affairs."

Referring to the fact that Britain has decided not to take part in a series of EU areas such as the passport-free zone, the charter of fundamental rights, the euro and justice and home affairs, the Polish politician inidcated that too many opt-outs will eventually mean a problem for Britain and the question of whether it is really a member of the EU.

A critical mass of opt-outs?

"It is fine until a certain critical mass [of opt-outs] is reached," said Mr Saryusz-Wolski adding that Britain is "close" to the point where the opt outs are no longer a problem for Europe but a problem for Britain.

Another EU official said that Britain - which has hung the spectre of a referendum over the talks if its 'red lines' are not met - is a more serious problem than Poland because it raises "more substantive issues."

Poland stole the headlines at a treaty summit of EU leaders in June by holding out until the bitter end for concessions on EU voting rules.

"Presentationally, it was very clever," said the official, adding that although Poland made "all the noise" at the summit, Britain "went behind the scenes" and got their wish list agreed.

Referring to the current talks, a UK official said they were proceeding at a "technical level" and that it was not a political issue but rather something that was left open by EU leaders that had to be legally cleared up.