Saudi Arabia said on Tuesday it had arrested more suspected Al- Qaeda members as the United States, Britain and Germany shut their embassies in the kingdom in response to warnings more "terror" attacks may be imminent. One Saudi security source told Reuters three men were detained in the Red Sea port city of Jeddah on Monday, and that one of them was "cooperating" by talking to police. But a U.S. embassy official said only two people had been arrested, both Moroccan, while Saudi officials were still searching for a third suspect of the same nationality. It was not clear if the arrests were linked to last week's triple bomb attacks of foreign residential compounds in the capital Riyadh, or similar bombings in Morocco on Friday. At least forty-one people died in the Morocco attacks, while 34 died in the Riyadh bombings, which were the first to indiscriminately target civilians in the oil-rich kingdom. Saudi Arabia said on Saturday that it had detained four Al-Qaeda suspects with prior knowledge of last week's bombings. Late on Monday, Saudi Arabia's ambassador to Washington, Prince Bandar bin Sultan, said he believed the bombers who struck in Riyadh were planning a much bigger operation. He said U.S. and Saudi intelligence were picking up "a high level of (electronic) chatter, regionally and in other international spots," which could indicate that something else was being planned. Saudi officials described the threat as "very serious" early on Tuesday. U.S. officials in the kingdom have warned that the network of Al-Qaeda agents operating in the kingdom was larger than initially thought. **EMBASSIES CLOSE*** "In response to information that some strikes may be imminent, the (Riyadh) embassy and consulates general in Jeddah and Dhahran will be closed on May 21, 2003," the U.S. embassy said in a statement on Tuesday. It said they would not reopen before Sunday, but gave no further details. U.S. and Saudi officials have blamed the blasts on Osama bin Laden's network, which is also blamed for the September 11, 2001 attacks on U.S. cities. Many Western expatriates left Saudi Arabia, after the blasts. Tension mounted sharply on Tuesday as authorities stepped up security in Riyadh and Jeddah, and some residents were told not to leave their compounds. The British Foreign Office said it would close its embassy and two other offices in Saudi Arabia from Wednesday until Saturday. Germany said it was closing its embassy and a mission to visitors at least until Friday over security concerns. "We have received credible information that further terrorist attacks against unspecified targets in Saudi Arabia are being planned and may take place imminently," a Foreign Office spokeswoman said in London. A Saudi gunman who was roaming around the U.S. consulate in Dhahran was also arrested on Monday. He did not fire any shots and the Saudi authorities described him as "mentally disturbed." **PHOTO CAPTION*** A Saudi army vehicle takes position outside the al-Hamra residential compound in Riyadh(AFP/File/Bilal Qabalan)