India agreed on Thursday to provide about $680 million in economic assistance to Mauritius for healthcare, infrastructure and maritime security projects, as New Delhi pushes for greater influence in the Indian Ocean nation in competition with China.

The assistance, in the form of grants and lines of credit, also includes support for development and surveillance of the marine protected area of the Chagos archipelago, which houses a U.S.-British air base on the island of Diego Garcia.

Britain in May ceded sovereignty of the Chagos Islands to Mauritius, but retained control of the military base under a 99-year lease.

India has historically backed Mauritius' claims over the islands and has supported the U.S. presence in the Indian Ocean to check the growing influence of China, which has close trade ties with Mauritius.

The marine protected area, where commercial fishing is banned, is one of the world's largest, covering a quarter of a million square miles - an area larger than the U.S. state of California.

The economic assistance was announced in a joint statement during the state visit of Mauritian Prime Minister Navinchandra Ramgoolam to India.

The support covers other development projects such as a new hospital, port redevelopment and restructuring, and also includes the provision of helicopters and a budgetary assistance of $25 million in the current financial year.