Germany threatens to call treaty conference over Poland's head

The move - the latest twist in tough negotiations on the future EU treaty - envisages a majority of the remaining 26 EU states calling the post-summit meeting without Polish approval, in a potential scenario not actually seen in Europe since the mid-1980s.

Some Polish officials have speculated that an open-mandate IGC could be useful for Poland, as it would give it a chance to debate the EU voting weights question in a less taut atmosphere than the current Brussels meeting.

One EU official explained that a majority of EU states could also decide on a mandate that excludes a voting debate, even though Poland would in the end have to sign any new EU treaty for it to become law.

"You could envisage a situation, in which Poland comes to the IGC and tries to talk about voting. Nobody would switch off the mike, but they would be gently reminded that this is not on the agenda, so their intervention would not be taken into account," he said.

But another EU official said the voting issue could still be raised under "any other business" and discussed during the intergovernmental talks.

Politically speaking, an IGC in which Poland was thoroughly gagged on voting would hardly persuade Warsaw to sign up to the final treaty. "Such a conference would be a waste of time," an EU diplomat warned.

The German development has seen French, Austrian and Luxembourgish leaders mobilise to try and get Poland to get on board.

French president Nicolas Sarkozy telephoned Polish prime minister Jaroslaw Kaczynski in Warsaw, after the PM in a spot on national TV said he felt the EU summit was heading for a Polish "veto" due to Berlin's "stubbornness."

Sweeteners still possible

Meanwhile back in Brussels, Austria's Alfred Gusenbauer and Luxembourg's Jean-Claude Juncker plan to talk to Polish president Lech Kaczynski, bearing a slightly sweeter offer than the original German package.

The original German package includes keeping existing "Nice treaty" voting weights until 2014, introducing a so-called "Ioannina Compromise" to help smaller EU states delay unfavourable decisions and giving Poland a few more MEPs.

Austria and Luxembourg plan to offer Warsaw keeping Nice until 2016. On top of this, Poland has also secured a new treaty clause on energy security, which talks of "a spirit of solidarity" in the event of an energy supply crunch.

Some EU officials suggest the deadlock may not be as profound as it seems.

Deal not out of reach?

"I heard that the Kaczynskis were quite close to accepting the deal, but that pressure from their coalition partners [the nationalistic League of Polish Families and Self-Defence parties] as well as critical [Polish] media coverage made them pull back," the contact said.

Poland's original voting demands - to rebase the whole EU vote population-weighting system or extend Nice until 2020 and get a "reinforced" Ioannina mechanism - go much further than anything on the table for now.

The voting debate is designed to address Polish fears that under the proposed new "double majority" voting system, big and rich EU states will be able to force through day-to-day EU funding and policy decisions that will make it harder for the Polish economy to catch up over the coming years.