By Luke Pachymuthu

SINGAPORE, Mar 20 (Reuters) Spot bulk freight rates for key Asian routes edged lower from week-ago levels, but heavy port congestion in Australia and healthy demand for grain cargo liftings in Latin America limited the losses.

Spot charter rates for modern panamax tonnages on the U.S.

Gulf-to-Japan route were pegged at W58-W60 levels, about 3 percent down from last week in Asia.

Time charter rates on the route fell about 5 percent from a week ago to around ,000. Shipowners and shipbrokers said the fall was a correction in prices rather than the start of a slide.

A Singapore-based shipbroker said shipowners had used the healthy demand in Latin American grain to bolster the market.

''But the market has come off that initial euphoria and we are seeing just a slight correction,'' the shipbroker said.

Argentina, the world's No. 3 producer and exporter of soybeans, will see production of grains and oilseeds at a record 94 million tonnes in 2007.

Forecasts in January for Brazil's soy crop output for 2006/07 (Oct/Sept) is expected to be around 56 million tonnes higher than earlier forecasted.

''There is still enough demand coming from the Atlantic to keep freight rates for the panamax- and larger-class sizes well supported,'' a Singapore-based shipowner said.

PORT QUEUES PERSIST Port congestion at Australia's Newcastle port continues to keep quality tonnage off the market, despite a decision to reinstate a queue management system.

UK-based shipbroker Galbraith estimated that there are at least 63 ships waiting to load at the port.

''Congestion remains at high levels in several areas with 63 ships off Newcastle at the time of writing,'' Galbraith said in its weekly report on Friday.

Australian competition regulator said it has been advised by miners that it could take until July before vessel queues thin out.

Tight tonnage and limited supply availability lifted benchmark Australian spot thermal coal prices to a one-month high on Tuesday to a tonne.

''Clearly the impact is on the logistics and supply side, and that we are not going to see any improvement anytime soon would suggest that freight is going to be supported in the medium term,'' a shipbroker said.

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