Robbers who tried to break into the grave of tycoon Li Ka-shing's wife were wasting their time, her elder son said yesterday. 'My mother was a Buddhist. Buddhists do not take valuable things as mortuary objects after their death. I think the robbers had some misunderstanding,' said Victor Li Tzar-kuoi, deputy chairman of Cheung Kong (Holdings). Mr Li visited the desecrated grave of Li Chong Yuet-ming - who died 16 years ago, aged 58 - after returning from overseas, as arrangements were made to repair the damage caused by the tomb raiders on Lunar New Year's Day. Accompanied by security guards, he went to the Hong Kong Buddhist Cemetery in Cape Collinson Road at about 10am. Asked if his mother's grave had been deliberately vandalised, Mr Li said: 'It seems that it is a tomb robbery case. Thieves only hammered the area where visitors stand and the tombstone is still in good shape.' Mr Li said he believed it would take a few days to complete the restoration. Nothing was stolen from the damaged grave, although some of its marble tiling was removed. The site was hidden under a plastic cover yesterday. Police officers were seen patrolling the cemetery and guards were stationed around the grave overnight on Monday. Four men were seen by two cemetery workers when they attempted to break into the grave at about 11pm on Sunday. The suspects, who were armed with knives and guns, tied up the two workers and robbed them of cash and valuables worth $70,000. The workers, who live on-site, freed themselves after nearly two hours and called police. A cemetery worker said all guards at the Chai Wan graveyard had been much more vigilant since the robbery. 'I am not too worried about the thieves, as all our guards are very alert now,' he said. The case is being investigated by police, but no arrests had been made last night.