By Oana Lungescu
BBC News, Brussels
Frantic diplomatic efforts in Brussels have failed to persuade Poland to lift a veto on the launch of a new strategic agreement between the EU and Russia.
Jaroslaw Kaczynski wants to export meat and plant products to Russia
European Commission President Jose Manuel Barroso promised to help Poland lift a Russian embargo on Polish meat, which he described as disproportionate.
But Poland wanted a clear link between the lifting of the ban and talks on the new agreement.
The deadlock is set to overshadow an EU-Russia summit in Helsinki on Friday.
Despite Mr Barroso's last-minute intervention and two days of intensive talks among EU ambassadors, Poland refused to budge.
It is the first time that one of the 10 member states which joined the EU in 2004 has blocked such an important initiative.
A spokesman for Finland, which holds the EU presidency, announced that the EU-Russia summit on Friday would not launch negotiations for a new framework agreement, which required a unanimous decision by all 25 EU countries.
Once again, the row highlights the deep divisions in Europe on how to deal with Russia, and is bound to strengthen Moscow's resolve to pick and choose among European countries.
The Helsinki summit was supposed to mark a new stage in relations, paving the way for a new strategic deal covering energy, migration, trade and human rights.
However, an EU spokeswoman played down the significance of the setback, saying the current, more limited, accord could be extended when it runs out in 2007.
She insisted the summit agenda would cover many other issues, including Russia's accession to the World Trade Organization and concerns over Georgia.
But it is hard to find any key area where the EU and Russia see eye to eye and the tone of the exchanges is getting harsher.
Russia has threatened to impose a new ban on all EU meat and animal products from January, when Romania and Bulgaria join the club.
EU enlargement commissioner Olli Rehn dismissed concerns over animal health in both countries and called Moscow's threat a political game in which the aim is to create pressure.