Tokyo - Police in Tokyo arrested a Foreign Ministry official on Monday on suspicion of setting fire to the Japanese Embassy in the Democratic Republic of the Congo.

Shinya Yamada, 30, who was working as the third secretary at the embassy in the Congolese capital of Kinshasa, was arrested in Tokyo. The diplomat returned to the ministry after the fire occurred on June 20.

Although no injuries were reported following the blaze which partially destroyed two floors of a private building in Kinshasa that served as the embassy's head office, arson was suspected as traces of an accelerant -- most likely gasoline -- were found following the police investigation, the ministry said.

Sources with knowledge of the matter also said the arson attack may have been financially motivated as money was found to be missing from the official building.

The foreign ministry, in a rare move due to diplomatic sensitivity, asked the Tokyo police to investigate the matter personally and found evidence showing that Yamada was the last person seen leaving the building soon after it was set ablaze. The building houses offices used by Japan's ambassador and counselor in Kinshasa.

Further investigations later turned up a gasoline canister at a private residence, presumably used by Yamada, police officials said.

Following the blaze, 20 personnel working at the embassy were transferred to another location, where diplomatic duties continued as usual, ministry officials said.

Following Yamada's arrest, Japanese Foreign Minister Fumio Kishida made a public apology for the alleged arson attack and said the ministry will deal strictly with the matter pending the outcome of further investigations.

Yamada who has been taken into custody has denied all allegations.