Washington and Prague agreed under the adminstration of George Bush, the former US president, to install a radar base in the Czech Republic as part of the US' plan to expand its missile defence shield against attacks from countries such as Iran.

Under the plan, a base would also be set up in Poland.

Lack of support

The pacts must be ratified by both houses of the Czech parliament and signed by the president for them to take effect.

The country's upper house has already backed the project, but the centre-right ruling coalition does not have enough votes in the lower house to ensure its ratification.

Topolanek has backed the project since he came to power in 2006, but some Czech politicians are worried the adminstration of Barack Obama, the US president, may overturn the plans.

Opposition parties and the majority of the population are against the scheme, with demonstrations against the proposal taking place in the Czech Republic over the last two years.

Russia has also strongly condemned plans to install the missile shield.

Topolanek has said the government will return to the issue after a Nato summit in early April.