Media playback is unsupported on your device Media caption The German deputy finance minister Steffen Kampeter has ruled out eurobonds, saying "debt is a national responsibility"

Germany's deputy finance minister has ruled out "eurobond-lite" plans to pool part of eurozone countries' debt.

Speaking exclusively to the BBC, Secretary of State Steffen Kampeter said "debt is a national responsibility".

"I don't see any strategies where we socialise and redistribute the bad political decisions made by some who are over-indebted."

The German government has already ruled out full "eurobonds" for now.

That may disappoint investors on international markets whose hopes had been raised by reports that the Germany might be inching toward the compromise mutualisation plan.

The plan, from Germany's so-called "wise men" group of private economic experts, would let countries with debt above 60% of GDP such as Greece issue eurobonds for debt above that level, which would then be paid down over a maximum of 25 years.

In effect, indebted governments struggling to borrow at affordable rates in the commercial markets would be able to take advantage of lower borrowing costs offered to countries within this joint bond, such as Germany.

It was put forward as an alternative to full eurobonds, which would involve eurozone economies clubbing together to issue bonds representing all 17 member nations.

Merkel warning

Earlier, Chancellor Angela Merkel said world leaders should not "overestimate" Germany's ability to resolve the eurozone debt crisis.

She told Germany's parliament that the country's options for rescuing the eurozone were "not unlimited".

Mrs Merkel called for more regulatory powers for the European Central Bank, and repeated that growth should not be financed by more debt.

Her speech came ahead of a meeting of G20 nations in Mexico this weekend.

Germany has been central in driving changes within the eurozone and backing the financial support given to debt-laden nations.

But, referring to the G20 meeting, she said: "I say to them Germany is strong, Germany is an engine of economic growth and a stability anchor in Europe... but Germany's powers are not unlimited."

She expected the debt crisis to be the main issue at the summit. "Our country will be the centre of attention. It's a fact, all eyes are on Germany because we are the biggest European economy and a major exporter," Mrs Merkel said.

But Europe would only find a way out of the crisis with a strong "political union" that mandated greater fiscal co-ordination and oversight to put member countries on a "solid foundation", she said.

Mrs Merkel has resisted calls that austerity measures in the eurozone should be relaxed in the hope that it would boost growth. "We must all resist the temptation to finance growth again through new debt," she said.

She also called for the European Central Bank to play a "bigger role" in overseeing banks to avert further turmoil in the industry.

'Misguided'

"We need a more independent supervisory authority," she said in an apparent criticism of the European Banking Authority.

Berlin has said the current system is too dependent on national regulators and, in particular, under-estimated Spain's banking problems.

"The EBA conducted stress tests on all European banks a year ago, and the national oversight bodies were very involved," Mrs Merkel said.

"We are now seeing the result. Spanish banks are in quite a different situation than the tests appeared to show."

She said that national banking authorities, on which the EBA relied for its information, had provided results that were as positive as possible "out of misguided national pride".

Mrs Merkel has long argued against what she called "miracle solutions" to the debt crisis, saying that only closer political and fiscal union can solve the problems - something she accepted was a "Herculean task".

Worries in the financial markets that there is still no clear roadmap towards a solution for the eurozone were underlined on Thursday when Spain's borrowing costs hit at a new euro-era high, just days after the country agreed a bailout of its bank sector.

Italy's borrowing costs also jumped sharply amid fears that the country's debt woes were deepening.

Meanwhile, the Prime Minister of Slovakia has said that Greece should quit the euro bloc if it fails to honour its commitments.

Robert Fico said Europe should do all it could to keep Greece within the bloc, but that the country had to adhere to the terms of its bailout package.

With anti-austerity political parties expected to do well in Greece's general election on Sunday, Mr Fico told a news conference: "If the Greeks do not meet the commitments they have made, do not meet their financial commitments, do not repay loans, Slovakia will demand that Greece leaves the eurozone."

The remarks echo similar comments made by the European Council President, Herman Van Rompuy. "We will do our utmost to keep Greece in the eurozone while it is respecting its commitments," he said.

A strong showing for Greece's increasingly popular left-wing and anti-austerity party Syriza is likely to strengthen expectations that the country will leave the eurozone.