The traps, which can hold an animal held alive for hours with smashed leg bones and other severe wounds, are outlawed in Britain and have long been the target of animal welfare campaigners.
Six years ago, a European directive banned them and halted the import of furs from nations which use the traps.
But the European Commission has never implemented the trade ban for fear of opening a trade war with the main fur exporters, Canada, the US and Russia. As an alternative, the Commission has negotiated a deal on humane trapping standards which would apply both to the exporters andEuropean countries too.
Environment ministers from European Union states will vote on this deal, covering 19 species of mammal, at their meeting in Luxembourg tomorrow. The matter will be decided by qualified majority voting, so Britain cannot veto it. But it may find enough allies to block it; Austria and Sweden could side with the UK.
Canada still uses the steel- jawed leghold as a restraining trap (one which keeps its victims alive) for five species - the racoon, bobcat, lynx, coyote and wolf. If Europe signs up to the agreement, Canada promises to phase it out within three years.
Looking on anxiously is the British fur trade, which has been trying to persuade the environment minister, Michael Meacher, to drop his opposition to the agreement. Mr Meacher has told them he is too busy for a meeting, although he has met the RSPCA, which sees the agreement on humane trapping standards as a betrayal of animal welfare.
Although years of campaigning against fur has made the trade almost disappear from Britain's fashion stores, more than half the international fur trade is handled by British traders, brokers and insurance firms. The British Fur Trade Association says the business is worth around pounds 300m a year.
"It seems crazy to us to think our government wouldn't sign this," said Peter Zeitlin, who leads the association and hails the agreement as "a massive leap forward for animal welfare".
The US and Canada have warned that were Europe to reject the agreement, and then implement the ban on fur imports, it would go to the World Trade Organisation, the international court which decides on trade disputes. If that found against the EU, Europe would have to pay compensation or itself be the target of legitimate trade sanctions from the complainants.
The deal on trapping standards has taken years to negotiate. Along the way, the US has dropped out, saying that because trapping regulations are set by individual states rather than the federal government, it cannot guarantee to implement them.
Now both the European negotiators and those from Canada and Russia say they can go no further; environment ministers have to accept or reject the agreement, but they cannot request amendments. "That would be a mission impossible," said a Commission source.
Under the agreement (see panel), within a few years time, any mechanical trap used to catch animals for pest control or food as well as for fur, must meet basic standards limiting the amount of pain and wounding they cause.
Supporters say it will give a worldwide boost to the development of less cruel traps of all designs. Critics say it is a fudge which sanctions continued use of the horrific leghold traps. It does not cover snares, nor the two species most frequently trapped in Britain - the fox and the rabbit.
The European Commission was itself divided on the issue, with the trade commissioner, Sir Leon Brittan, in favour of the agreement, and the environment commissioner, Ritt Bjerregaard, opposed.
Sir Leon got the backing of most commissioners, so Ms Bjerregaard will advise the environment ministers to accept this week. "She will do her duty," said the commission source. A senior official in the Canadian Foreign Ministry said: "If we get Europe, Canada, Russia and then the US on board, then the rest of the world will follow."
But a spokesman for the Department of the Environment said: "We don't think this agreement goes far enough, so we'll vote against and urge the EU to bring in the trade ban."