Mauritius was battening down the hatches on Monday as an intense tropical cyclone approached, with flights cancelled and public transport halted on the Indian Ocean island nation.

The Mauritius Meteorological Services (MMS) issued a Class 3 cyclone warning, saying the estimated gusts in the centre of Cyclone Freddy could be around 300 kilometres (190 miles) an hour.

It said the storm was centred about 275 kilometres to the northeast of Mauritius at 7 am (0300 GMT) and moving west-southwest at an increased speed of about 30 kilometres an hour.

"On this trajectory, Freddy continues to dangerously approach Mauritius and represents a direct threat," the weather service said.

"As Freddy approaches Mauritius, storm surge is likely to cause coastal inundation in risk areas. It is therefore strictly advised not to go to sea."

Flights have been cancelled to a number of international destinations, and all flights between the main island and the outlying isle of Rodrigues have been halted.

"Air Mauritius is closely monitoring the situation with the authorities and will keep passengers informed of developments," the national carrier said on its website.

Public transport has been halted, and people have been urged to take all necessary precautions to keep safe.