MONROVIA- Liberian President Ellen Johnson-Sirleaf said on Friday some of her closest aides would be screened before they could restart work after fire destroyed her office while three other leaders were in the building.

The Executive Mansion caught fire on Wednesday during a visit by the presidents of Ghana, Ivory Coast and Sierra Leone, in Monrovia to celebrate the restoration of mains electricity to parts of the capital for the first time in 15 years.

"I am told my office and the office of the minister of state were destroyed," Johnson-Sirleaf, who took office in January as Africa's first elected female head of state, told reporters.

"We are going to put the entire Executive Mansion staff under a screening process before we restart our work. That will be everybody. From the minister of state down to the gardener."

Police officials have said they cannot rule out sabotage as the cause of the blaze, a potential embarrassment for Johnson-Sirleaf as she tries to rebuild the West African nation after a 14-year civil war that wrecked its infrastructure.

The National Security Agency, headed by Johnson-Sirleaf's stepson Fumba, is leading the investigation into the fire.

Liberia's war was one of the most brutal in modern African history, killing a quarter of a million people and ending when warlord and then-president Charles Taylor -- now in The Hague on war crimes charges -- fled to exile in Nigeria.

Power cables were torn down and water pipes ripped up for scrap metal by fighters, many of them child soldiers high on drugs, during the conflict, which ended in 2003. The return of mains electricity was supposed to be a symbolic step forward.