"Publication of the list [of national key points] would prejudice the defence and security of the country," said Viwe Notshe SC, for the State.

"The real issue is whether what has been disclosed is enough and whether further disclosure will prejudice the security of the department."

The court heard there were 200 national key points.

Notshe said the disclosure of places where research was done on clothing would not prejudice the country's security.

However, it would be a "different story" when it came to a place where research was done on chemical weapons.

The Right2Know Campaign (R2K) and the SA History Archive (SAHA) want the police to reveal the national key points under the Promotion of Access to Information Act (PAIA).

National key points are protected from being photographed or identified as key points, and are understood to include military installations and services or factories which are considered strategic.

In 2012, a request made to the police for a list of key points was refused.

R2K said on Sunday that civic organisations had complained that the secrecy surrounding national key points had been used "to undermine" the right to know and to protest in public spaces.

The PAIA sets out a number of grounds for the refusal to grant access to information.

These include defence, security and international relations of South Africa, its economic interests and financial welfare, and protection of commercial information of a third party, such as trade secrets and commercial information.

In May last year the police ministry said the National Key Points Act was being reviewed.