Zimbabwe's national airline has grounded two Chinese-built planes further making it difficult for the troubled airline to service its routes.

Air Zimbabwe bought the two MA-60 turboprop planes in 2005. A third was donated by the Chinese earlier this year.

A report in The Standard, an independent weekly newspaper, says the two planes have been grounded for more than two weeks. The report said the planes were grounded because expired spare parts had not been replaced.

The newspaper, quoting sources at Air Zimbabwe, said the planes were kept flying after the expiration of parts due for replacement after 1,000 flying hours. The source was quoted as saying the planes reached 1,000 hours last December. The third plane is still flying because it has yet to reach the hours required for replacement.

The MA-60s service domestic and regional routes. The planes are the most tangible evidence of President Robert Mugabe's look-east policy. Since the breakdown of relations with traditional western trading partners over alleged human rights abuses by his government, Mr. Mugabe has been cultivating trade with eastern countries notably China.

The Standard reports another of Air Zimbabwe's planes, a long-haul Boeing 767, has been transferred from London to Germany for service, after being grounded in the British capital for weeks. But the paper says the national airline is struggling to get parts to repair the plane because suppliers are demanding cash upfront.

Air Zimbabwe's passenger fleet has dropped from more than 20 aircraft in the 1980s to less than 10. In the past few years the airline has had cash flow problems that have seen it temporarily suspended by the International Air Transport Association for non-payment of dues.

Earlier this year, Air Zimbabwe Chief Executive Officer Oscar Madombwe blamed the airlines problems on the shortage of hard currency to buy equipment and new planes.

Last November, the airline ran out of jet fuel and failed to service its routes. The fuel problem persists and sometimes aircraft have to fly via Lilongwe in Malawi to refuel, which Madombwe said is expensive.

Zimbabwe is currently facing its worst economic crisis since independence in 1980. Fuel, food and foreign currency are in short supply and inflation at close to 1,200 percent is the highest in the world.