Poland's upper house of parliament may ban trade and plantings of genetically modified (GMO) seeds on Thursday and put Warsaw on a collision course with Brussels for endorsing a law that breaks EU rules.

The chairman of the Senate's agriculture committee said he expected senators from the ruling conservative Law and Justice party and several fringe groups to support the draft law, which has already been approved by the lower house of parliament.

"Senators from Law and Justice will back the bill and I have not heard any objections from several other parties, so it should pass," Jerzy Chroscikowski told Reuters.

The legislation would still have to get final approval from lower house deputies after the Senate vote. It also has to be signed by the president to become law.

Poland's plans for what is effectively a national GMO ban have drawn criticism from the European Commission, the EU executive, for threatening to break EU laws, especially those that aim to preserve the bloc's single internal market.

The Commission takes the view that if a region wants to ban GMO crops, such a restriction has to be scientifically justified and crop-specific -- not a blanket ban on all biotech seeds or crops.

"We might have to consider excluding an individual GM product from a given area if, for scientific reasons, it genuinely could not co-exist with non-GM crops in that area," said EU Agriculture Commissioner Mariann Fischer Boel. <

"But...we cannot simply ban all GM crops from an entire region because of hostility to GM products per se. Where a product has been shown not to be harmful, in principle the rules of the free internal EU market apply," she told a conference in Vienna earlier this month.

The Commission's position was put to the test a few years ago by an Austrian region whose proposed regional GMO ban was slapped down by Brussels. The Court of First Instance, the EU's second highest court, upheld the Commission's view last October.

Early last year Italy adopted a law imposing a ban on GMO crops until all its regions had agreed laws on how farmers should separate biotech crops from organic and traditional varieties. The Commission has already warned of legal action.

No biotech seeds have been planted in Poland and the ruling conservatives, who have long said they wanted to make Poland GMO-free, fear that potential future sowings of genetically modified crops could lead to contaminatation of other crops.

So-called coexistence laws -- or rules for separating biotech crops from organic and traditional varieties -- have become the most controversial area in the biotech debate across the EU.

Environmental groups in the bloc say no GMOs should be grown in Europe until an EU-wide coexistence law is in place. The biotech industry sees no problems in growing GMO crops next to non-GMO types.

Deputy Agriculture Minister Jan Krzysztof Ardanowski told Reuters this month the government wanted to ban sowing of GMO plants to protect Poland's image as an enviromentally friendly state and that it might seek changes to the bloc's biotech policy.