Public interest ought to override any ban exempting specific government bodies from releasing information once the Freedom of Information Act comes into force, Statewatch director Tony Bunyan said.
Statewatch is the independent non-profit making watchdog on European civil liberties.
"The application of blanket bans on all activities of specific authorities is building up trouble," he cautioned during a Citizens' Forum on the Freedom of Information Act organised by the European Parliament's Valletta office.
The Bill, which was given a second reading in Parliament this week, aims to give the public the right to access documents held by the authorities.
It lists several bodies, however, to which the Act will not apply, including the Electoral Commission, the Employment Commission, the Public Service Commission, the Attorney General's office, the National Audit Office and the Security Service.
It also exempts Cabinet documents and some documents falling under the Broadcasting Authority, among others.
Given that the very purpose of the law would be to "promote added transparency and accountability in government" such blanket bans would defeat the whole aim of the law.
"If there are bans, there must be an overriding public interest test," Mr Bunyan said. This would ensure that information in the public interest was released whenever someone eligible made a formal request.
According to the Bill's definition of "eligible person", one has to be resident in Malta for at least five years and be either a Maltese or an EU citizen or the citizen of a country that has rights by virtue of some treaty.
"I think that's nonsense... it should not matter where a person was from to be eligible to request information from a government whose decisions were affecting him," he argued. Asylum seekers, for example, do not fall under these categories but are closely affected by government decisions.
The Freedom of Information Act is not an end in itself. The end, he said, is not getting hold of the information but the way that information is used.
He gave an overview of Freedom of Information Acts in various EU countries, highlighting their strengths and weaknesses and picking important elements that made such a law effective. These included investing in training staff and having sufficient resources to provide an efficient service, compiling a departmental register of public documents to facilitate tracking them down and encouraging an active civil society that used the service.
Journalists Committee chairman Karl Schembri emphasised that the Act was a primary call against "a wide culture of secrecy". "This is not a journalists' campaign but one for the public at large," he said as he cautioned that enacting the law was not enough. It had to be followed up.
"We must remain vigilant and abreast of politicians' and civil servants' new ways of hiding information," he added.
Building on this point, the head of the European Parliament Valletta Office, Julian Vassallo, said the law also changed the way politicians and civil servants perceived their own acts.
The three main political parties included the law in their electoral programme and the legislation was a preamble to a major shift in a political culture that has been shrouded in secrecy for a long time, Dr Vassallo noted.