Prague  - The Czech government of Prime Minister Mirek Topolanek faced a vote of no-confidence on Tuesday, a test that threatens to undermine his country's presidency of the European Union.

Topolanek's fall at home would provide ammunition to his critics abroad, analysts said.

"(French President) Nicolas Sarkozy would be one of the first to make himself heard," said political scientist Petr Just, a lecturer at Metropolitan University in Prague.

"He would use it as an argument to support doubts whether the Czech Republic is mature enough to chair the EU," he said.

Analysts agreed that Topolanek's cabinet, which survived four such votes in parliament's lower house since taking power two years ago, has never been closer to a collapse.

"From the attempts to date this one has the biggest chance to result in the government's fall," said political scientist Jan Kubacek, who teaches at Prague's Charles University.

The cabinet's fate hangs on a handful of independent lawmakers, who had earlier defected from Topolanek's coalition ranks.

The centre-right three-party cabinet controls 96 votes in the 200-seat lower house, while the opposition Social Democrats and Communists command 97 votes. For the cabinet to tumble, they must win over another four.

While one Topolanek's rival within his Civic Democratic Party already indicated that he plans to aid the leftist opposition in toppling the cabinet, others remain mum.

At a press conference on Monday, the premier called on lawmakers to act responsibly at a time of the economic crisis and the country's EU presidency.

He said he planned last-minute talks with several defectors but admitted to holding little sway in the house. "Do not expect any miracles from me," he said.

Were the cabinet to fall on Tuesday, President Vaclav Klaus would hold the key to future developments.

While Klaus declined to shed light on his potential steps, analysts expect him to re-appoint Topolanek with a condition that he secures 101 votes in favour of a new cabinet, an impossible demand without forming a grand coalition with opposition Social Democrats.

Topolanek said his party would prefer an early election in the summer if attempts at forming a new government would fail.

The cabinet's potential collapse has the potential to hinder the premier's two key foreign policy projects.

In a claim disputed by some analysts and legislators, government officials indicated that the fate of the EU's reform pact, the Lisbon Treaty, was at stake.

In February, the Czech Republic was the last member state to begin voting on the pact, which Topolanek signed on behalf of the Czech Republic in December 2007.

The accord currently awaits a vote in the upper house of parliament dominated by Topolanek's senators, the majority of whom rejects it in line with the premier's foe, Klaus. However the premier's senators who support the pact in combination with the pact's supporters from other parties are seen as sufficient for approval.

"It is possible that Topolanek would no longer have the political power to push the Lisbon Treaty through the upper house," said Ivo Slosarcik of the Prague-based Europeum thinktank.

Senator Jiri Liska of Topolanek's Civic Democrats countered that the cabinet's collapse would not have much sway. "It would not change the senators' minds," he said.

However, analysts believed that the government's collapse would kill Czech-US missile defence treaties, already put on ice owing to a lack of support in the lower house.

"The US radar is under a much greater threat than the Lisbon Treaty," Just said. (dpa)