RIYADH- Saudi Arabia's transport ministry has signed contracts worth 1.7 billion riyals ($453.3 million) to extend 23 roads across the kingdom as part of a plan to upgrade its infrastructure.

The contracts are part of 75 projects worth 2.7 billion riyals signed so far this year, said an emailed statement, without naming any of the 18 companies that were awarded the contracts.

The kingdom has invested heavily in infrastructure projects in the past including ports, railways, roads and airports with its cities growing significantly in recent decades.

Under its ambitious reform programme, Vision 2030, the government is spending billions of dollars to expand public transport systems in the capital Riyadh and other big cities in partnership with the private sector.

The plan is for the private sector to operate much of the kingdom's transport infrastructure, including airports and sea ports, with the government acting as a regulator.

(Reporting by Marwa Rashad; Editing by Louise Heavens) ((marwa.rashad@thomsonreuters.com; +966114632603 ; Reuters Messaging: marwa.rashad.thomsonreuters.com@reuters.net))