ITINERANT hawkers have been dealt a blow by Hongkong's keep clean campaign and will be swept from the territory's streets in the name of a greener environment. The hawkers will be given three years to retire or move to market stalls, following an Urban Council decision to abolish their licences as of April 1, 1996. An assistant director with the Urban Services Department, Mr Yu Hon-ping, said itinerant hawkers had become a public nuisance in Hongkong's busy streets, where they often blocked traffic. Under special licence conditions, itinerant hawkers can move around and trade wherever they like in the territory. But Mr Yu said they tended to flock to congested areas, such as ferry piers and cinema entrances, where they obstructed pavements and roads. Those dealing in wet foods also created hygiene problems. ''Itinerant hawkers are not currently prohibited, but they create the same sorts of problems as illegal hawkers,'' he said. Some itinerant street vendors also accepted bribes to protect illegal hawkers, helping them to recover goods seized by the Urban Services hawker patrol, Mr Yu claimed. The Urban Services Department is offering itinerant hawkers three options. They can retire early and accept a $30,000 payoff, exchange their itinerant licence for a fixed pitch licence, or become market tenants at a preferential rent. The chairman of the Federation of Hongkong, Kowloon and New Territories Hawker Associations, Mr Wut Chiu, said the Urbco payoff as fair. He estimated that about a quarter of the 3,500 itinerant licensees sell out immediately.