CAIRO - Security guards sealed off the Ministry of Social Solidarity in Cairo Sunday after an anonymous phone call triggered a bomb alert in the building, the police have said. "A phone call by an unknown person claimed that there was a bomb at the Minister's office and the treasury office has triggered an alarm. All precautionary measures have been swiftly taken and the entire building was immediately evacuated," a security official said, adding police and rescue services had been notified about the incident. "The Ministry building had been sealed off and evacuated," he said. A switchboard worker has received the phone call early in the morning and reported it to the authorities concerned, the official said. They ordered that the building be immediately evacuated after receiving the suspect phone call. Social Solidarity Minister Gouda Abdul Khaliq said that all initial tests and search in his office and the treasury room by explosive experts had proven negative. This is the first bomb alert since the January 25 Revolution. Under Egyptian law threats and false alerts are taken seriously. The phone caller, if arrested, could face three years in prison and a hefty fine if found guilty. The Army has warned that it would take harsh steps to prosecute hoaxers on charges of disrupting public order.