Surgeons yesterday reattached the left hand of a Taiwanese tourist after it was chopped off and thrown into the sea by robbers on Tuesday night. The operation on Yang Shanyu, 34, lasted about 13 hours, a spokesman at the Conde de Sao Januario Hospital said. Mr Yang was 'as well as can be expected under the circumstances', he said. Doctors expected to know within 72 hours if the hand would be rejected. The hand, minus a finger which was cut off in the attack, was recovered by police divers. Mr Yang told police he had been assaulted by two men brandishing meat cleavers as he walked with a Macau woman along the Praia Grande waterfront at about 8pm on Tuesday. The two fled with Mr Yang's diamond-studded gold watch. A police spokesman said the exact circumstances and motive for the attack were unclear, although detectives close to the investigation did not exclude the possibility the attack was a 'bloody warning' by triads. Mr Yang's companion appeared to have only a vague recollection of the attack. Shih Yi-hun, director of the Taipei Trade and Tourism Office in Macau, confirmed the victim's Taiwanese citizenship and said he arrived in Macau recently with a tour group.