Bosses who hire mainland visitors will face tougher laws under a Security Bureau proposal to combat two-way permit holders working in the SAR illegally. The proposal follows a 50 per cent rise in average monthly arrests of illegal workers in the first two months of this year. The bureau plans to amend regulations to make it easier to bring employers found hiring illegal workers to court. The move is also aimed at stemming the tide of overstayers. About 250,000 mainlanders come to Hong Kong on two-way permits each year. Principal assistant secretary Raymond Fan Wai-ming said: 'On average, about 10 per cent of mainlanders overstay their permits. 'So we might have about 25,000 overstayers a year. Most overstayers are independent travellers coming to visit relatives,' he said, although some overstayed and found jobs. In January and February, 999 illegal workers were caught in immigration operations. This was a higher monthly average than last year. A total of 3,992 illegal workers were arrested for the whole of last year, or a monthly average of about 330. Mr Fan said the situation was not out of control but admitted prompt action was needed. 'We want to make employers hiring overstayers face the same punishment as those using other illegal workers,' he said. At present, many employers can escape prosecution because it is difficult to prove the employment relationship between an overstayer and an employer. 'In some cases, an overstayer does not know who his boss is,' a bureau spokesman said.