Two Leighton subsidiaries have won new contracts worth a total of $437 million.

Leighton’s 45 per cent-owned Middle East associated Habtoor Leighton Group won a $US316 million ($A302.96 million) contract to build new medical centres in the centre of Riyadh in Saudi Arabia.

The work will be carried out with a local contractor under a joint venture arrangement.

Domestically, Leighton construction subsidiary Thiess has won a $134 million contract to build a tunnel for the Santos Gladstone liquefied natural gas (GLNG) project in Queensland.

The 4.3km tunnel will connect the LNG plant on Curtis Island with the mainland, Thiess said.