Taiwan on Friday expressed shock and regret over Gambia's surprise announcement that it had broken off ties with the island after 18 years in its "strategic national interest".

"Our government express shock and regret that Gambian President Yahya Jammeh sent a letter to our embassy in Gambia on November 14 to inform us the immediate termination of ties," vice foreign minister Simon Ko told a news conference in Taipei.

Gambian President Yahya Jammeh has pardoned Lebanese businessman Hussein Tajudeen, four months after he was expelled from the west African nation for questionable economic activities.

An official statement issued by the president's office said the multimillionaire was free to return to Gambia as of October 25.

The Gambia on Friday banned imports of frozen chicken legs after expelling one of the country's most powerful business magnates for stocking groceries months past their sell-by date.

Lebanese-Gambian multimillionaire Hussein Tajudeen, a former close friend of President Yahya Jammeh, was kicked out of the country this week for "engaging in undesirable business activities".

The Gambia introduced a raft of new laws on Tuesday criminalizing male prostitution, cross-dressing and the singing of abusive songs in public.

The move reflects the "current socio-political realities" in the impoverished west African nation, Justice Minister Lamin Jobarteh told parliament, before lawmakers signed off on amendments to the criminal code act which also outlaw being irritating in public and "refusing to maintain" oneself.

Benin President Thomas Boni Yayi was elected the African Union Chairman Sunday, taking over the one-year post from Equatorial Guinea's President Teodoro Obiang Nguema, officials said.

"I want to congratulate the new chairman of the African Union... Boni Yayi," said Obiang, the outgoing chairman, speaking after the official announcement at the AU summit meeting in the Ethiopian capital.

The search for the world's first malaria vaccine received a boost with the release of early results from a major clinical trial showing it cut risk by about half in African children.

The vaccine known as RTS,S is made by the British pharmaceutical giant GlaxoSmithKline's lab in Belgium, and is the first of its kind to attempt to block a parasite, rather than bacteria or viruses.

Senegal has cut diplomatic ties with Iran, accusing it of delivering weapons to separatist rebels in its restive southern Casamance region where 16 soldiers have been killed since the end of December.

A cache of Iranian weapons concealed as building material intercepted in Nigeria in October 2010, was found to be one of several shipments passing through Gambia and destined for the Casamance rebel movement.