By Camillus Eboh

ABUJA (Reuters) - Sierra Leone's deputy high commissioner in Nigeria has been released four days after being kidnapped in the northern state of Kaduna, officials of the two West African countries said.

Major-General Alfred Nelson-Williams, who was abducted on Friday while traveling from Nigeria's capital, Abuja, to Kaduna state, was freed on Tuesday at around 4 p.m. (1100 EDT).

The diplomat has been reunited with his family after having "regained his freedom", Nigerian police spokesman Don Awunah said in a statement, adding Williams was "in good condition". Further details about the release were not disclosed.

The kidnappers had demanded a ransom of 40 million naira ($141,985). Sierra Leone's minister of information, Mohamed Bangura, confirmed that the diplomat was freed on Tuesday but did not say whether or not a ransom was paid.

Kidnapping for ransom is a common problem in parts of Nigeria, Africa's biggest energy producer and most populous country.

($1 = 281.7200 naira)

(Additional reporting by Umaru Fofana, in Freetown; Writing by Alexis Akwagyiram; Editing by Mark Heinrich)