PRAGUE, Jan 29 (Reuters) - The Czech government should drop the resistance it put up along with Britain to joining the EU's budget discipline pact, a junior party in the ruling coalition said on Tuesday.

Putting pressure on Prime Minister Petr Necas, who has struggled to hold his government together through a string of defections, the pro-EU TOP09 party said it wanted a commitment to join the pact this year.

The Czech Republic and Britain were the only countries in the 27-nation European Union that did not sign the pact when it was agreed a year ago.

The Czech's national debt is lower than the EU average and its budget deficit is under control. The mildly euro-sceptic Necas, head of the centre-right Civic Democrats, decided to stay outside the pact for the time being.

But TOP09 sought a change of policy as part of a revision of the government's agenda for the time left until a 2014 election.

'Sometimes even the bigger party must understand it has to make a compromise,' TOP09 Chairman Karel Schwarzenberg said.

Necas, head of the centre-right Civic Democrats, has left the door open to joining the pact, possibly after the strongly anti-EU President Vaclav Klaus steps down in March this year, but has made no commitment to sign.

The Civic Democrats said they disliked being given an ultimatum but were ready to talk.

'I hope this is not being led by a desire to provoke a clash in the coalition,' Necas said in a statement.

He said there could be a debate on joining the fiscal compact but only after the parliament adopts a 'financial constitution' setting independent Czech limits on debt.

He also called for a law that would require a referendum on any eventual move to adopt the euro.

Defections have narrowed the government's ranks to 99 in the 200-seat lower house of parliament, but it has survived five no-confidence votes since it took power in 2010, the latest on Jan. 17, with the help of independents.

It will come under more pressure from newly-elected leftist President Milos Zeman, who has said the cabinet should quit due to its budget-cutting policies and falling popularity.

Zeman, who will replace Klaus in March, does not have any legal authority to remove the cabinet.

Opinion polls have shown the leftist opposition would win a parliamentary election held now. TOP09 has however been bolstered by Schwarzenberg's strong showing in the presidential election, where he lost to Zeman in a run-off round.

(Reporting by Jan Lopatka; Editing by Ruth Pitchford) Keywords: CZECH EU/

(jan.lopatka@thomsonreuters.com)(+420224190474)(Reuters Messaging: jan.lopatka.thomsonreuters.com@reuters.net)

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