Tung Chee-hwa has to include rent in his election expenses for the time spent on his campaign while in his office at government headquarters, according to the Electoral Affairs Commission. But Mr Tung's election office said the additional cost was expected and the sum would have only a small effect on the Chief Executive's campaign spending. The commission said yesterday Mr Tung would not be misusing public resources by discussing his campaign at the Central Government Offices. But he should designate money in proportion to the time he spent discussing campaign issues with aides at his office during working hours. He has a $9.5 million election expenses fund. The commission also said the Chief Executive should keep a record of the time he spent meeting members of his campaign team each day on election-related matters. A spokeswoman for the commission said Mr Tung should assess the value of the Chief Executive's Office and come up with a 'reasonable rate' of how much it would cost - per square foot - a month if he had to rent it. Legislator Lau Ping-Cheung, representative of the architectural, surveying and planning sector, estimated the 10,760 square foot office would fetch about $30 per square foot per month if it were a private office. But a spokesman for Mr Tung's Election Office refused to disclose whether it had assessed the value of the office. 'We will keep records of the time Mr Tung spends on the campaign,' he said, adding that the campaign office thought it would have only a minor effect on the overall campaign fund.