German authorities issued international arrest warrants on Friday for two Arab men in connection with last week's terrorist attacks in the US.

Ten days into a national investigation prompted by evidence that three of the suicide hijackers had recently lived in Hamburg, Kay Nehm, the chief federal prosecutor, issued warrants for Ramzi Binalshibh, 29, a Yemeni national, and Said Bahaji, 26, a German of Moroccan origin. They are being sought on charges of forming a terrorist organisation, of hijacking four aircraft and of at least 5,000 counts of murder, Mr Nehm said.

Both are suspected of plotting last week's attacks along with the three hijackers - Mohammed Atta, Marwan Al-Shehhi and Ziad Jarrah - and other, as yet unknown, suspects.

Mr Nehm said "the necessary logistics" for the attack meant that it had been planned "since 1999 or before". He added that there was no proof of links to Osama bin Laden but that such ties were being investigated. Mr Bahaji left Germany for Pakistan on September 3, leaving behind his wife and small child, while Mr Binalshibh was last seen in Hamburg in August. The exact whereabouts of both men is unknown.

Both the suspects were students in Hamburg. Mr Binalshibh was known to be a close friend of Mr Atta, and had tried in 2000 to attend a flying school in Florida attended by two of the other hijackers but had failed to get a US visa, Mr Nehm said. Mr Bahaji had an "interest in radical Islam and held extremist Islamic and anti-western views", according to the federal prosecutor's office.

Police have raided dozens of apartments across Germany and gathered more than 2,000 potential leads from members of the public. No arrests have been made.

In Hamburg, university staff and former friends of the three suspects expressed shock at their alleged involvement in last week's atrocities, because in public they appeared to hold moderate views.