Bersih 4 T-shirts were banned on the eve of the mega rally last August because they were a security risk, the government said.

Home Minister Ahmad Zahid Hamidi added there is also no absolute guarantee to freedom to assemble in the federal constitution.

He said this yesterday in a written reply in Parliament to Kashturi Patto (DAP-Batu Kawan), who asked what procedures the minister went through before issuing a ban on any yellow clothing or printed materials with the term 'Bersih 4'.

This comes as Bersih obtains leave to challenge the ban which came hours before the Kuala Lumpur rally, to among others call for Prime Minister Najib Abdul Razak's resignation.

Ahmad Zahid said the ban was issued the under the Printing Presses and Publications Act 1984, which bars any printed material that can cause unrest.

He added the materials were also banned because the coalition for clean and fair elections, Bersih, is not registered with the Registrar of Societies.

Nor did Bersih obtain permission to hold a rally, he said.

"Even though freedom to assembly is enshrined in the federal constitution, it is not an absolute freedom.

"It is conditional under Article 10(2) in the interest of national safety and public order," he said.