(PARIS) - The European Central Bank spent massively for a second day to buy Irish and Portuguese debt bonds on Friday, traders said revealing the scale of the ECB's onslaught to douse the eurozone debt crisis.

The head of the ECB, Jean-Claude Trichet, warned earlier this week that the markets had underestimated the will of European Union bodies to defend the euro.

He then signalled on Thursday that the ECB would continue its exceptional buying of bonds issued by eurozone governments under pressure over big debts and deficits and on Friday he pushed the same message even further, calling for member states to take the steps to be equal to the challenges ahead.

It has emerged that even as Trichet spoke on Thursday, the central bank was making wave after wave of government bond purchases.

This pushed down the borrowing rates which eurozone governments under pressure over their public finances, and notably Portugal and Spain, must pay.

In late trade Friday, benchmark Irish 10-year bond yields had fallen to 7.906 percent from 8.297 percent on Thursday, with the equivalent Portuguese bond at 5.714 percent, after 5.854 percent.

On Wednesday, the Irish bond was trading at above 9.0 percent and the Portuguese bond at around 6.4 percent.

The Spanish 10-year bond on Friday was at 4.985 percent, down from about 5.004 percent on Thursday, with the Italian rate slightly higher at 4.389 percent against 4.360 percent.

"The ECB is continuing its purchasing which began massively two days ago," bond strategists at French banks BNP and Natixis said.

At BNP, strategist Patrick Jacq said: "I would not be surprised if it (the ECB) has bought between 3.5 billion and 5.0 billion euros' (6.6 billion dollars') worth of debt in three days, mainly Portuguese and Irish debt, and to a lesser extent Greek debt."

Traders said that the ECB was buying in blocks of 100 million euros and that the overall amounts were sharply higher than previously when it took about 700 million euros to 1.0 billion euros per week up to about the middle of November.

Last week, the ECB began to accelerate its purchases, spending 1.3 billion euros as a rescue for Ireland was being worked out and the price of bonds issued by several eurozone governments, notably Portugal and Spain dropped, pushing up their borrowing rates.

At Natixis, strategist Jean-Francois Robin said: "Since Wednesday and above all Thursday it (the ECB) has moved into a much higher gear."

In a French radio interview Friday Trichet described euro as a "credible" currency. "There is no crisis for the euro as a currency," he said.

Trichet's remarks on Thursday were closely followed by financial markets, which had expected clearer guidance than the ECB gave on whether it would, and to what extent, maintain and extend its exceptional bond-buying measures.

Many analysts commented that Trichet's remarks, from the viewpoint of removing uncertainty about the risks of buying eurozone debt, had been disappointing.

Until recently, the ECB had spent about 67 billion euros since it began its exceptional measure of buying eurozone government bonds in May.

Goldman Sachs bank analysts calculated last week that it had already bought 17 percent of the debt issued by Greece, Ireland and Portugal and estimated it could end up holding 50 percent of their debt.

The ECB, as the central bank, can create as many euros as it deems necessary but to prevent this injection of money from stoking inflation, it withdraws from the economy equivalent amounts of money by offering attractive deposit rates to banks.

The ECB also makes cheap money available to the banking system by other refinancing means -- the banks in Greece and Ireland are heavily dependent on this funding.

The ECB had earlier indicated that on Thursday it would signal how it would wind down this galaxy of special measures but the ratcheting up of the eurozone debt crisis in recent weeks dictated that it had to at least hold the line for a while longer.