German authorities Saturday arrested a fourth man on suspicion of involvement in an al-Qaeda-linked group's alleged plot to attack Iraqi Prime Minister Ayad Allawi during his visit to Berlin this week. Meanwhile, the three Iraqis already in custody for their alleged roles in the plot denied the accusations against them during questioning Saturday by a judge, Der Spiegel newsweekly reported Saturday. The judge will decide whether to issue an arrest warrant against them. The fourth suspect, a man with Lebanese citizenship, was arrested in Berlin on suspicion of supporting a foreign terrorist organization, federal prosecutors' spokesman Hartmut Schneider said.U.S. authorities have linked the group to al-Qaeda. German authorities have said Ansar al-Islam has about 100 supporters in the country. Prosecutors did not release the three suspects' names. One of them, the suspected head of an Ansar-al-Islam cell in the southern German state of Baden-Wuerttemberg, has been under investigation by Stuttgart authorities since October 2003, Der Spiegel reported. He was brought to the attention of German authorities by prosecutors in Milan, Italy, after a telephone call with a key terror suspect in Italy, the magazine reported. Before Allawi's visit, investigators who had the three suspects under surveillance noticed an increase in activity, phone calls and suspicious movements by one suspect that amounted to evidence of plans to attack, prosecutors say. The suspects' phone calls grew more hectic after initial intelligence led officials to cancel a Thursday night meeting between Allawi and Iraqi exiles in Berlin, prosecutors say. Allawi said the threat was part of his everyday life, the Munich-based Sueddeutsche Zeitung daily reported Saturday. "But, we will not give up, even when a few terrorists want to force us to," the newspaper quoted him as saying at a Friday evening event. Allawi left Germany later Friday for Russia, wrapping up a three-nation trip.