CARNARVON - South African officials and scientists on Monday celebrated a milestone towards building the world's largest radio astronomy instrument, which is co-hosted with Australia and aims to unlock mysteries of the universe.

The construction launch outside the remote town of Carnarvon, Northern Cape, marks the next phase of developing a complex instrument aimed at revealing events since the cosmic dawn, when the first stars and galaxies were formed.

South Africa said it will add 133 dishes to its 64-dish MeerKAT radio telescope to create SKA-Mid in the next phase of developing a so-called Square Array Kilometre (SKA).

"Today has huge significance for all of us ... working towards building a large, exploratory instrument that can serve our community and advance a number of scientific frontiers," Joseph McMullin, deputy director-general at the SKA Observatory (SKAO) intergovernmental organisation said.

MeerKAT, which will be incorporated into SKA-Mid, has delivered images of phenomena including stellar nurseries and the chaotic region around the supermassive black hole at the centre of our galaxy, some 25,000 light-years from earth.

Chosen for its remoteness, with hills providing an extra shield against radio interference, the vast protected reserve around Carnarvon is the main African base for hundreds of antennae that could eventually be sited as far afield as Kenya and Ghana.

The dishes are designed to connect with each other to form one giant telescope and with the new additions, expected to be operational by 2030, enhanced image clarity and resolution.

While tripling the number of dishes at MeerKAT to form a mid-frequency instrument, Australia will host a low-frequency telescope array of 131,072 antennae, each two metres tall and resembling Christmas trees, officials said.

(Reporting by Wendell Roelf; Editing by Bhargav Acharya and Alexander Smith)