Department director Li Pang-kwong said a fall in Financial Secretary Donald Tsang Yam-kuen's rating could be attributed to his proposals for a wider tax base and the introduction of a sales tax.

Mrs Chan's rating, which increased from 6.19 in January to 6.28 this month, was the highest among SAR government officials.

Mr Tsang's rating of 6.27 was the second highest, although it represented a 0.2 point fall from the previous survey.

The sharpest decrease was seen in the rating of Leung Chun-ying, convenor of the Executive Council, which fell from 4.72 last January to 4.45 this month.

He was also the least well-known official.

Twelve per cent of interviewees did not know who he was and 6.8 per cent did not know what he had done recently.

Emily Lau Wai-hing of The Frontier secured the highest rating among leaders of major political groups, although there was a slight drop from 5.36 in January to 5.21 this month.

She was followed by Democratic Alliance for the Betterment of Hong Kong (DAB) chairman Tsang Yok-sing, who had a rating of 4.81.

Mr Tsang was the only legislator to see an increase in approval ratings. Mr Li said this was the result of the DAB's success in last November's district council elections and also its more active role in the community.

Close to 40 per cent of interviewees did not know who Hong Kong Progressive Alliance chairman Ambrose Lau Hon-chuen was, and 7.2 per cent were not familiar with his recent work. He received the lowest rating among legislators.

The rating for Democratic Party chairman Martin Lee Chu-ming dropped from 4.98 to 4.63. Mr Li attributed the fall to the party's internal strife and the competition with DAB - which appeared to be more active than the democrats at district level.