* Tonnage list grows in Pacific, Atlantic oceans - broker
* Lack of coal cargoes weigh on freight rates
By Keith Wallis
SINGAPORE, Aug 20 (Reuters) - Freight rates for capesize bulk carriers are set to slide further next week, after falling to their lowest level in five weeks, due to a mounting supply of tonnage and uncertain cargo demand, ship brokers said on Thursday.
"There's too many ships in the Pacific. There's a lot of ballasters (empty ships) sailing to Brazil," a Singapore-based ship broker said.
Capesize freight rates from Australia to China could fall to around $5-$5.20 a tonne next week on this overcapacity, with rates from Brazil to China at $12.50 to $12.75 a tonne, a Shanghai-based capesize broker said on Thursday.
While major charterers including Rio Tinto and BHP Billiton were active this week, just a handful of spot iron ore cargoes were concluded with virtually no coal fixtures.
A raft of transatlantic coal and iron ore cargoes helped push capesize rates to their highest level in eight months in early August, but this business has evaporated causing spot freight rates to steadily fall.
"Coal used to be the all-important dry bulk commodity," said Peter Sand, chief shipping analyst at shipping industry lobby group BIMCO.
The steam coal trade between China and South Africa, which accounted for 8 percent of China's steam coal imports in 2013, has disappeared due to the overall decline in China's coal imports and a greater proportion of volumes from Australia and Indonesia, Sand said.
"China's coal trade with South Africa was beneficial to seaborne trade as the sailing distance is twice as long as from Australia and Indonesia. As of right now it has been over a year since a shipment of steam coal heading for China left South Africa," Sand said.
Charter rates for the Western Australia-China route dropped to around $5.74 a tonne on Wednesday, down from $6.30 a tonne a week ago, although the last concluded fixture was already lower at $5.60 per tonne, the Singapore broker said.
Rates for the Brazil-China route fell to $13.58 per tonne on Wednesday, against $14.77 per tonne last Wednesday, the highest since Dec. 4.
Freight rates for smaller panamax vessels will likely climb next week on strong U.S. and east coast South America grain volumes, a Singapore-based panamax ship broker said on Thursday.
Panamax vessels transporting these grain cargoes are being chartered for about $8,500-$9,000 per day, compared with $6,500 per day for a transpacific voyage, the broker said.
Freight rates for smaller supramax vessels could also climb, supported by South American grain cargoes, Norwegian ship broker Fearnley said in a note on Wednesday.
The Baltic Exchange's main sea freight index fell to 1,031 on Wednesday from 1,093 on the same day last week. (Reporting by Keith Wallis; Editing by Gopakumar Warrier)