According to a senior party member's statement on Monday, Germany's rival Social Democrats (SPD) will support Berlin's input to a Greek salvage only if Chancellor Angela Merkel promises to put more effort to battle market speculators.

It has been reported that cabinet of Merkel is due later on Monday to consent Germany's 22 billion euro share of a rescue package, activated by European funding ministers on Sunday. On Friday, the lower and upper houses of parliament are likely to vote on it.

Joachim Poss, Deputy Head of the SPD parliamentary party stated, "Mrs. Merkel must boost her credibility in fighting speculation and for an effective financial transaction tax in Europe. Mrs. Merkel must make clear statements today".

On Monday, Merkel is yet to have discussions with leading lawmakers.

It has been reported that Merkel does not require the SPD's backing to get parliamentary consent, although she would wish to have cross-party support on an important issue like such.

It has been said that the SPD could freeze the program by being adamant on the hearings of the committee.

For long, Merkel had opposed any German bailout of Greece, mainly due to stiff public resistance before a crucial regional election on May 9.

But, she stooped to pressure from the EU and IMF and showed support for the rescue during the weekend.