All Official Secrets Act-stamped material and documentary exhibits in a lawsuit over Malaysia’s 2018 withdrawal of a review bid over the country’s sovereignty dispute with Singapore over Pulau Batu Puteh is now no longer accessible to the public.

The Kuala Lumpur High Court this morning allowed an application by the prime minister and the Malaysian government for a sealing order over the exhibits.

In effect, this means that now only parties in the suit and...