Environmentalists are excited by the latest action, but rural leaders have accused the Government of stripping them of their right to use their own land.

Planning Department figures show 150 hectares of agricultural land - mainly in Yuen Long and North District - are being illegally used as storage for containers and trailers, dumping sites, car parks, and factories. Ponds and rivers have been reclaimed, giving rise to serious drainage and pollution problems.

The Government blamed the illegal change of land use for the widespread flooding in the New Territories during Typhoon Dot in September, which reportedly damaged one-third of Hong Kong's farmland.

However, of 174 cases of unauthorised development of rural land since the enactment of the ordinance, only 11 landlords and operators have been convicted. Fines were as low as $7,500.

The Director of Planning, Dr Peter Pun Kwok-shing, admitted the situation was unsatisfactory and said it was due to the lengthy procedure of serving warning and stop notices.

It might take longer than a year before an alleged offender could be brought to court under such a system.

Dr Pun said his department would now apply more frequently Section 21 of the ordinance, to simplify prosecution procedures.

The section empowers the department to prosecute without going through the process of serving notices.

Dr Pun refused to predict by how much this would shorten the process, but believed it would create a stronger deterrent.

The Central Enforcement and Prosecution Section - staffed by 35 town planners, surveyors, and inspectors - would step up work in these areas.

District Planning Officer Li Chi-kwong, who heads the section, said: ''In the past, we had to go through different units to process one case. The new centralised section will enable quicker investigation and prosecution.'' Conservancy Association spokesman Hung Wing-tat welcomed the move and urged the Government to introduce laws to ban the change of use of agricultural land.

''Prosecution is important. But the crux of the problem is that developers or landlords can apply for planning permission to change the land use.

''We believe once the land is zoned as, say, agricultural, such land use cannot be changed,'' Mr Hung said.

In the past two years, 32 of 148 exemption applications were approved by the Town Planning Board.

Ping Shan rural committee leader Leung Cheuk-pui said the Government had no right to decide on land use for the landlords.

''We own the land and we rent it out to earn some money. It is none of the Government's business.''