Unscrupulous Hong Kong tour operators could soon need to be a bit more cautious about conning compatriots from the Chinese interior: that gullible-looking sightseer waving a wad of red renminbi might really be an undercover agent.

After a spate of reports of rampant rip-offs by the Hong Kong tourist trade, authorities are stepping up efforts to ensure mainland travellers get a fair deal in the former British crown colony.