Tips, which used to be a "gray area" income for Chinese tour guides, are set to be made legitimate in the country with the release of a guideline to safeguard the rights of guides, the Shanghai Morning Post reports.

The new rule, jointly issued by the China National Tourism Administration and two other government departments, stipulates that travel agencies should explore performance-based incentive systems for tour guides based on volunteer payments made by tourists.

However, the rule does not define pricing criteria for tipping tour guides, and is causing concern that voluntary tipping may in reality turn into a compulsory payment and thus increase a traveler's economic burden.

Travel agencies say it is unnecessary for tourists to have such worries. Travellers can file complaints with their agency if tour guides extort tips from them.

Industry insiders and tourism experts say relevant standards and matching measures are needed for the tipping mechanism to effectively encourage tour guides to provide quality services. Otherwise, tipping could bring new troubles.