Iranian oil revenues have fallen around 45% in the last nine months because of Western sanctions, a leading Iranian politician says.

Gholam Reza Kateb, an MP on the national planning and budget committee, said the country's economy as a whole was in trouble.

In a further sign of the crisis, the oil ministry has stopped selling fuel to some airlines over unpaid bills.

Oil exports account for a majority of the Islamic republic's revenue.

Mr Kateb said the steep export drop was revealed in a parliament report by Oil Minister Rostam Qasemi.

"On the basis of the report, oil sales are down 40% and income has dropped 45% in the last nine months," Mr Kateb told the semi-official Isna news agency.

In recent weeks, the oil minister has insisted that Iran has successfully bypassed oil sanctions.

Meanwhile, a number of airlines have been forced to cancel their flights, BBC News reported.