Libya's state shipping company says it has halted oil shipments to Switzerland in protest at the brief arrest of leader Muammar Gaddafi's youngest son. It threatened further action if the Swiss did not apologise for the arrest. Geneva police held Hannibal Gaddafi for two days after he and his pregnant wife allegedly hit two of their staff. The couple face charges of bodily harm, threatening behaviour and coercion. They have denied any wrongdoing over the alleged incident on 15 July. Costly row? The stopping of oil shipments comes a day after the Swiss foreign ministry complained of Libya taking "retaliatory measures", such as forcing Swiss firms to close Libyan offices. Libya's General National Maritime Transport Company - which has links to Hannibal Gaddafi - said in a statement that it had halted all oil shipments to Switzerland. The firm handles most of Libya's oil exports. However, the AFP news agency reported that oil carried by commercial vessels would not be affected. In a joint statement with the national port authority, the company also said ships sailing under the Swiss flag had been banned from entering Libyan ports. It is a row that could prove costly to both countries, says the BBC's Imogen Foulkes in Geneva. Switzerland imports at least half its crude oil from Libya but Libya owns a large oil refinery in Switzerland. Libya's influential people's committees have also called for Libya to withdraw its deposits from Swiss banks if an apology for the arrest is not forthcoming. 'Worrying measures' The Swiss foreign ministry said on Wednesday that Libya had "taken a number of worrying retaliatory measures" for Mr Gaddafi's arrest since he was released on bail on 17 July. It said Swiss companies ABB and Nestle had been ordered to close their Libya offices and that Swiss staff there had been arrested. Flights between Libya and Switzerland had been reduced, Libya had stopped issuing visas to Swiss citizens and Tripoli had recalled some of its diplomats from Bern, the Swiss foreign ministry said. The ministry also said it had sent a delegation to Libya to explain Mr Gaddafi's arrest. It has advised Swiss citizens not to travel to Libya until further notice. It is not Hannibal Gaddafi's first brush with the law. In 2005 he was convicted by a court in France of assaulting his girlfriend. Source: BBC