A bomb attack on a housing complex in the Saudi capital Riyadh bears all the hallmarks of al-Qaeda, senior US and Saudi officials say.

Seventeen people are killed and more than 100 injured in the blast, mostly foreign Arab workers.

Italian Defence Minister Antonio Martino says he believes al-Qaeda elements to be involved alongside Saddam Hussein loyalists in an attack on a police station in Iraq in which 18 Italian policemen and nine Iraqis died.

"The enemy we have to deal with is the same one - global terrorism - which is striking wherever possible," Mr Martino said.

Following two major bomb attacks on British-linked targets in Istanbul, there are separate claims of responsibility from two allegedly al-Qaeda connected groups.

One unconfirmed report said a group calling itself Abu Hafz al-Masri Brigades had admitted to carrying out attacks on the British Consulate and the HSBC bank offices in Istanbul, which left 27 people dead and more than 450 wounded.

Another claim came from a caller to the semi-official Anatolia news agency, who said that al-Qaeda and a Turkish militant group IBDA-C were jointly responsible.