TREASURY Secretary Donald Tsang Yam-kuen vowed to solve within three years the problem of under-spending of capital works expenditure. The assurance was given as it was revealed that under-spending on capital works in the last financial year was close to 11 per cent. The revised estimate of the total of capital works has been put at $29.4 billion, from the original $33 billion. Under-spending over 30 per cent of the total expenditure of public works projects in 1991 and 1992 has led to criticism of the Government's estimate of total spending. It has also been attributed to the embarrassing increase in estimated surplus. Mr Tsang yesterday attributed the under-spending to factors including weather and difficulty in site acquisition for public works projects. 'Sometimes when we embark on capital projects we have to clear either illegal occupation or resume land from private owners. Sometimes we are not able to clear the site as early as expected . . . The progress of work has been affected. Site availability is a key factor,' he said. One case was the redevelopment plan for Rennie's Mill. Resettlement of the residents there was held up by the failure of the Government and the residents to agree on compensation. Independent Emily Lau Wai-hing queried whether the under-spending in the capital works item would mean delay in progress of works projects. Mr Tsang said the target of works expansion was set in accordance with the five per cent rate of economic growth. Mr Tsang , tipped to be the first local Chinese financial secretary, said they would continue to improve the system. 'We hope the problem will disappear in two to three years.'