Security forces have fought and surrounded Somali kidnappers hours after they abducted a Spanish and an Argentine aid worker with the medical charity Medecins sans Frontieres (MSF).

"The police captured two of the kidnappers after a heavy exchange of gunfire, and they are now surrounded," Puntland Trade Minister Abdishamad Yusuf Abwan told Reuters.

In the latest such abduction in the semi-autonomous northern Puntland region, the women's car was ambushed by a gang with machineguns in Bosasso port as they drove to a hospital.

But they were pursued by authorities and engaged in a gunfight shortly after, locals said.

Spain's ambassador in Nairobi, Nicolas Martin Cinto, was quoted by Spanish news agency Efe as saying the kidnappers of Spanish doctor Mercedes Garcia and Argentine nurse Pilar Bouza had surrendered and asked not to be killed.

A Spanish Foreign Ministry spokeswoman also said of the drama that "it looks like this is going to be resolved". The abduction in Bosasso port came two days after gunmen in Puntland released French journalist Gwen Le Gouil, whom they kidnapped and held for eight days demanding $80,000 in ransom. Known for its relative stability compared with chaotic south Somalia, Puntland has, however, become increasingly associated with kidnappings, hijackings and piracy.

"Six men armed with guns approached me, blocking the road," the MSF pair's driver, who asked not to be named, told Reuters. "They hit me very badly and kidnapped the women in their car."

Local authorities said they were chasing the abductors.

"We have sent troops to track down the kidnappers," said Yusuf Mumin Bidde, deputy governor of the Bari region, which includes Bosasso.

Foreigners in Somalia often fall foul of clans by failing to seek permission to travel through their territories. Somali kidnappers are known to treat their captives well and almost never kill them, viewing them as an investment on which they expect a return in the form of ransom.

The women's translator said the assailants beat up their chauffeur before ordering them into another car and driving them off.

"The abductors had a Toyota Surf and they blocked the way we were going," added the translator, who asked not to be named. An MSF spokesman, Javier Sancho, said the women had been working on a nutritional project for the Spanish branch of the international charity.