Prague - Czech and US negotiators opened three days of talks Wednesday on a treaty that defines status of US troops to be stationed at a planned US missile-shield radar base on Czech soil, the Czech Defence Ministry said.

"It is possible that the negotiations would be finalized by Friday but we rather expect one more round," ministry spokesman Jan Pejsek said.

One contentious point obstructs a speedy deal, he said. The officials negotiating the so-called Status of Forces Agreement remain divided on taxes for contractors at the base.

"Americans want no or low taxes. Czechs demand the same taxes that are paid by any other company," Pejsek said.

Prime Minister Mirek Topolanek told reporters Wednesday that Czech Republic's security council resolved "not to change or soften" their negotiators' mandate.

The agreement is to complement the finished main diplomatic treaty, whose signing in Prague by US Secretary of State Condoleezza Rice and her Czech counterpart Karel Schwarzenberg is planned for early May.

Both agreements must be approved by parliament where the centre-right governing coalition so far lacks clear support for the US project.

While Czech-US talks are close to an end, a deal on placing 10 interceptor missiles in Poland is lagging behind.

Washington has so far failed to win over Moscow, which rejects the US plans to place missile defence bases in the former Soviet satellites.