SYDNEY (AFP) — Australia on Sunday warned of a 'high risk' of terror attacks on domestic and international flights in and to the United States, urging citizens to be vigilant while in the country.

'We advise you to exercise caution and monitor developments that might affect your safety in the United States because of the risk of terrorism,' the Department of Foreign Affairs and Trade said in a travel advisory.

The department urged travellers to monitor the media for information about possible new security threats.

'The United States Department of Homeland Security's Advisory System Threat Level is at Orange for all domestic and international flights, indicating a 'high' risk of terrorist attack,' it said.

'It is at Yellow or 'elevated' for all other sectors, indicating a significant risk of terrorist attack.' ....