Freetown - A senior Sierra Leonean diplomat kidnapped in Nigeria last week is alive and in good health, officials in Freetown said on Monday.Alfred Nelson-Williams, defence attaché and deputy head of Sierra Leone's high commission in Abuja, was abducted on July 1 while travelling to Kaduna, 200km north of Nigeria's federal capital, according to a security official in Kaduna state."We are certain he is alive," presidential spokesperson Abdulai Baytraytay said in a televised address."Sierra Leone has sent a special envoy to Abuja as an intermediary to open a line of communication between the alleged kidnappers and our high commission," the spokesperson said, adding that security considerations meant he was unable to explain how he knew Nelson-Williams was alive.Sierra Leonean "President Ernest Bai Koroma is very concerned over the kidnap... and is in around-the-clock contact with the president of Nigeria on the matter," said Baytraytay.Citing a diplomatic report, Deputy Information and Communications Minister Cornelius Deveaux said the kidnapped official was "in good health"."We continue to have complete confidence in the ability of the Nigerian authorities to handle the matter" Deveaux said, adding that he had no information about whether a ransom had been demanded. There have been media reports that the kidnappers had sought a $40m ransom.Kidnapping for ransom is very common in Nigeria.