WASHINGTON (CNN) -- The United States has closed its embassies and other government installations in the West African countries of Ghana and Togo due to security threats, the State Department said Monday.

The Togo embassy was closed Monday, and the Ghana embassy will be closed through at least Wednesday, a statement said. Both closures could be extended.

The State Department said Americans in both countries should "avoid all U.S. facilities" on the affected days and should telephone any U.S. facility before visiting.

The embassy in Ghana's capital, Accra, received at least one bomb threat, according to an official at the U.S. Information Agency, which maintains an office there.

The Accra embassy was closed for three days after a bomb threat earlier this month, but reopened on August 17.

In Togo, a small country that borders Ghana to the east, a U.S. Marine guard confirmed that the embassy in the capital of Lome had been closed for security reasons, but declined to provide further information.

A senior State Department official said both embassies had been operating with reduced staffs since the August 7 bombings of the U.S. embassies in Nairobi, Kenya, and Dar es Salaam, Tanzania.

Those bombings killed 258 people, including 12 Americans. More than 5,400 people were injured.

Several U.S. embassies have undergone security alerts since the bombings. Last Thursday, the State Department announced that the U.S. Embassy in South Korea had received unconfirmed information that terrorist action might be taken against U.S. installations or people in that country.

The State Department also announced last Friday that the U.S. Embassy in Kampala, Uganda, had received unconfirmed information of "a threat against American citizens from a Uganda rebel group."

The embassy in Kampala remains open, but "security awareness" has been heightened. No further details of any specifics of these threats has been made available.