The government said international misunderstanding may be behind Hong Kong's fall in an annual index measuring rule of law as they vowed to step up efforts to better explain the situation here.

The World Justice Project, which compiles the index, scored Hong Kong in the top 10 jurisdictions worldwide for order and security, as well as absence of corruption, but it ranked lower for constraints on government and for fundamental rights.

Overall, the SAR fell three spots to rank 22nd among the 140 countries and regions, with its score decreasing by 2.8 percent from a year before.

In a statement on Wednesday evening, the government said the SAR still ranked "higher than some western countries which often unreasonably criticise the rule of law and human rights situation" of the city.

"We believe that the slight adjustment of Hong Kong's ranking in some aspects is possibly due to the lack of an accurate and overall understanding of the real situation of the city," a government spokesperson said.

"We will step up our efforts in explaining Hong Kong's situation to ensure that others have a correct understanding of the system in Hong Kong."

The spokesperson pointed to the SAR's ranking of sixth worldwide in terms of order and security and said it is "sufficient proof of the important role of the Hong Kong National Security Law in maintaining the order and security".

Separately, Chan Chak-ming, president of the Law Society, the professional body representing solicitors in the SAR, said in a statement on Thursday that the group was studying the rule of law index in detail.

"We value any objective, independent data or rankings on the rule of law as reference material for the government and the legal sector to make improvement as necessary," he said.

"Preliminarily, whilst we note that Hong Kong's overall rule of law score ranks 22 out of 140, falling three positions since last year, we also note that Hong Kong has been ranked number four in East Asia."

The Washington-based World Justice Project said its findings were based on surveys of 150,000 households and 3,600 legal practitioners and experts worldwide. It found that adherence to rule of law fell in 61 percent of the 140 territories it surveyed this year, continuing a recent downward trend.