European stocks inched lower on Friday as a rally sparked by European Central Bank's huge cash injection loses steam, while Brent crude futures dropped as concerns of a supply disruption from Saudi Arabia abated.

U.S. stock index futures pointed to a slightly lower open on Wall Street, with futures for the S&P 500, Dow Jones and Nasdaq 100 down 0.1-0.3 percent.

The FTSEurofirst 300 .FTEU3 index was down 0.1 percent around midday, surrendering early gains after Spain Prime Minister Mariano Rajoy said the country will base its 2012 budget on a deficit target of 5.8 percent of gross domestic product, a softer goal than the official EU-agreed objective of 4.4 percent.

Stock indexes are losing speed, although it looks too early to start selling. Equities still have a 3 to 4 percent upside potential, said Gerard Sagnier, Aurel BGC technical analyst, in Paris.

The euro fell 0.8 percent against the dollar to a 1-1/2-week low of $1.3210, with traders pointing out large stop-loss sell orders triggered through $1.3270.

German Bunds gained ground as investors booked profits on higher-yielding euro zone government debt following this week's sharp rally that drove Italian two-year yields to their lowest levels in 15 months.

The ECB's half a trillion euros in cheap, 3-year loans added to the banking system this week has helped fuel a 2-1/2 month recovery rally in risky assets, driving down bond yields of debt-stricken euro zone governments such as Italy.

We had a stress in the inter-bank market and there were fears that some banks would not be able to fund themselves. The ECB's actions have greatly reduced that risk, said Klaus Wiener, chief economist at Generali Investments, which manages about 330 billion euros ($440 billion).

However, the equity rally that had been sparked by the ECB's first long-term funding operation in mid-December showed signs of exhaustion on Friday, after European stock indexes failed to break above key resistance levels.

YEN, BRENT FALL

The yen dropped to nine-month lows versus the dollar, falling after data showed persistent negative price pressures in Japan which are likely to keep the Bank of Japan's focus on monetary easing and undermine the currency.

The yen has been hurt by the BOJ's surprise monetary easing in February, while the dollar found some reprieve this week after U.S. Federal Reserve Chairman Ben Bernanke stopped short of signaling more stimulus.

The Japanese data is persistently deflationary and the Bank of Japan is ready to do all they can to turn inflation positive, said John Hardy, currency strategist at Saxo Bank.

But I do think dollar/yen is getting a little over-extended at these levels, he added.

Brent crude futures sank more than 1 percent to below $125 a barrel after surging 5 percent to an 11-month high a day earlier, as concerns of a supply disruption from Saudi Arabia abated.

Brent topped $128 a barrel in late post-settlement trade on Thursday, reaching levels not seen since July 2008, when the growing economic crisis drove oil to record peaks of more than $147 a barrel.