Germany's opposition Social Democrats threatened to abstain from Friday's parliamentary vote on a 750 billion euro rescue package unless the government backs a motion to push for an international financial transaction tax.
The Bundestag lower house is due to vote on the euro zone rescue package on Friday, probably around midday (1000 GMT).
Although Chancellor Angela Merkel's centre-right coalition does not need the SPD to get the bill through the Bundestag, it wants as much cross-party backing as possible due to stiff public opposition to bailing out weaker euro zone states.
At a meeting on Thursday, the SPD agreed to present its own bill on a transaction tax on Friday, said Joachim Poss, deputy head of the SPD in parliament.
If Chancellor Angela Merkel's conservatives and her Free Democrat (FDP) coalition allies support the bill, the SPD will vote for the government bill on the 750 billion euro package.
If not, the SPD will abstain or vote against the bill, said Poss. "A well-founded abstention could be an answer," he said.
The SPD says it does not oppose the package, to which Europe's biggest economy may have to contribute up to 148 billion euros in guarantees, but insists that the financial sector should shoulder some of the burden.
Merkel, facing public anger over the measures, has sought to defend the package, arguing that it is essential to defend the European common currency which, she says, is in danger.
However, if Merkel hoped a unilateral move this week to ban the naked short-selling of euro government bonds and related transactions in credit default swaps (CDS) would win over the SPD, she will be disappointed.
The country's financial regulator also banned naked short sales of shares in Germany's 10 leading financial institutions.
The solo move irritated the European Commission and some other EU states, who complained the measure was not coordinated in advance.
Two weeks ago, the SPD abstained from a vote allowing Germany to contribute up to 22.4 billion euros to a 110 billion euro rescue plan for debt-ridden Greece.
A handful of abstentions and votes against are also expected from the ranks of Merkel's own party on Friday. A test vote showed seven conservatives voting against and two abstaining, party sources said.
The bill, provided it is passed by Bundestag lawmakers, is expected to go to the Bundesrat upper house later on Friday.
A regional vote last week robbed Merkel of her majority in the Bundesrat but as no coalition in the state of North Rhine-Westphalia has yet been agreed, Merkel should be safe as the house's new composition will not have taken effect.
ReutersLast Mod: 20 Mayıs 2010, 18:55