Global stocks were mixed on Monday with European markets firming after the ECB signalled strong support for eurozone debt and on G7 pledges to bolster the economy, but Asian shares fell and gold surged.

Concerns about weakening growth saw 'safe haven' investment gold shoot to a record high point above $1,700 an ounce. The euro rose against the dollar after Standard and Poor's had on Friday downgraded its rating on US debt.

"With Asian markets continuing to fall overnight, it looks like we are in for another volatile week," said Dermot O'Leary, economist at Goodbody Stockbrokers in Dublin.

"Leaders have come out with strong statements that they will do what is needed, but markets will be looking for real action."

London's benchmark stocks index rose 0.56 percent in early deals, Paris jumped 0.75 percent while Frankfurt was flat, reversing initial falls and a slump for equities last week.

US debt bond prices firmed slightly in Europe, causing the signalled borrowing rate for the United States to edge down, despite the rating downgrade and concerns it would send rates upwards..

"The FTSE 100 quickly recovered from opening losses of 1.0 percent on Monday to post gains, providing some relief for investors," said City Index analyst Joshua Raymond.

The London market had plunged almost 10 percent last week on fears of another vicious global downturn, wiping around £150 billion from the combined value of the FTSE's 100-listed companies, which include HSBC, Shell and Vodafone.

As nervous global markets re-opened, financial chiefs and central bankers of the G7 nations, which include Germany and the United States, pledged to "take all necessary measures to support financial stability and growth."

Barclays Capital analysts downplayed the statement, saying it "sought to bolster confidence but offered only consoling words."

Asian stocks tumbled on Monday as traders focused on last week's historic downgrade of the United States' credit rating, which compounded concerns over the world's biggest economy as well as the global outlook.

The Tokyo stock market closed down 2.18 percent, Hong Kong tumbled 2.11 percent, Seoul sank 3.82 percent and Sydney shed 2.91 percent.

"No one really fully understands the full implications of this credit downgrade, which is why we have seen the market sold off hard," said Ben Potter, analyst at trading group IG Markets.

"It's a classic case of sell first, ask questions later."

The stock market falls were echoed by big losses in oil futures while gold prices surged to a new record of $1,715.75 an ounce as investors moved out of risky assets.

S&P on Friday cut the US debt rating to AA+ with a negative outlook from the top-notch triple-A for the first time.

The decision sparked criticism from Washington, with Treasury Secretary Timothy Geithner saying the agency had shown "terrible judgement" and assuring investors US Treasuries were as safe as ever.

In foreign exchange deals on Monday, the euro advanced to $1.4335 from $1.4282 on Friday.

With concern running high that eurozone debt could plunge the world into a new financial crisis, the European Central Bank promised to make major purchases of eurozone government bonds.

The ECB said it would renew bond purchases after Italy and Spain had announced new measures and reforms to control their finances and boost their economies, and France and Germany pushed for full and rapid implementation of a plan to avoid future crises.

Madrid stock prices surged 3.31 percent in early trading as Milan rocketed 4.0 percent. The pressure on Italian and Spanish government debt meanwhile eased sharply.

The yield or the rate of return earned by investors on the Italian 10-year government bond was 5.417 percent, down sharply from 6.189 percent at the close Friday.

The Spanish 10-year bond was at 5.285 percent after 6.271 percent, with both doing even better than in opening trade.

Rates above six percent are thought to be unsustainable over the longer term for government financing and the pressure on Italy and Spain had raised fears that they too may need a bailout after Greece, Ireland and Portugal.