A government proposal to tax people for crossing the border into the mainland undermined the 'one country, two systems' concept and would be unfair for business travellers and families trying to save money by shopping in Shenzhen, critics said. Mr Tsang said yesterday the planned tax would boost government coffers. The administration was considering imposing the levy on all types of land travel, but would first consult train and bus operators before making a decision. Thousands of people who regularly travel to Shenzhen to take advantage of cheaper prices would be hit by the tax, expected to be about $10. But critics said the charge would hurt relations with mainland city governments. Pun Sun-cheung, who shops and visits relatives occasionally, said: 'It's absolutely absurd. How can you charge departure tax for travelling within one country?' A Shenzhen curtain shop manager said he disagreed with the tax. 'Things here are cheap. It's beneficial to struggling families. They are to punish people for coming here. There are other ways to help the Hong Kong economy.' Mr Tsang said the tax would generate revenue, not discourage people from going to Shenzhen. 'Such a tax would yield significant revenue, a much needed boost to our medium-term finances,' he said. It would be fair as departures by air and ferries were already taxed. Schoolchildren and truck drivers would be excluded from the levy.