Hong Kong officials had been trying to get a response from the mainland after the two officers, one carrying the handcuffs, were arrested with five others on Mount Davis Road on June 16, prompting suspicions they had been on a covert surveillance mission.

In a letter to the Legco panel, the Hong Kong bureau said the Guangdong Provincial Public Security Department had confirmed that two of the seven were serving public security officials, while the other five worked for a rental car company in Shenzhen. 'The purpose of their visit was sightseeing and shopping,' it said.

Police were making further inquiries with mainland security authorities and were still investigating the 'suspected offences' of the arrested people.

Mr To, a Democratic Party legislator, said he was not convinced and called on Chief Executive Tung Chee-hwa to raise the issue with the central government.

'[They were] wandering around at night armed with handcuffs; there is no way that I would believe [they were tourists],' he said.

Mr To said Beijing should take a tougher stance against officers who exercised power outside their jurisdictions, or others would be encouraged to conduct operations posing as tourists.

Another panel member, Ip Kwok-him, said he believed the arrested officers had entered Hong Kong as tourists without informing their units about the true purpose of their visit.

'It may be true that they entered Hong Kong as tourists,' said Mr Ip, vice-chairman of the Democratic Alliance for Betterment of Hong Kong. 'But the point is they did something they shouldn't have and the people concerned should shoulder the responsibility.'

The seven were arrested outside Cape Mansions in Mount Davis Road after a complaint from a member of the public.

Their identities and their true purpose for entering Hong Kong remained a mystery for weeks.

In an interview with the South China Morning Post last week, Police Commissioner Dick Lee Ming-kwai said that in deciding whether to press charges, police would have to determine whether those arrested had good reason to be on Mount Davis Road and possess the pair of handcuffs.

He referred to a case in February when an FBI agent was let off with a warning after being caught carrying ammunition as he tried to board a flight for Bangkok at the airport, after arriving in Hong Kong from New York.

'So taking prosecution action is not a must. The point is whether you've got a reasonable explanation,' Mr Lee said.

He said the men, if public security officers, had breached the 1997 agreement between Hong Kong and Beijing to follow Interpol protocol and not carry out enforcement in each other's jurisdiction.

Mr Lee declined to be drawn on whether Guangdong authorities were being unco-operative. But he did not see a need for public security officers to pursue cases in Hong Kong secretly, as co-operation channels existed.