* China c.bank: inflation outlook "not optimistic"
* Urges traders to buy c.bank bill, repos
* China paper says room for more policy tightening (Adds details)
BEIJING/SHANGHAI, April 6 (Reuters) - China still has too much cash in its economy so the battle to tame inflation is a challenge, a central bank official told traders on Wednesday, suggesting more monetary policy tightening lies ahead.
Just a day after China raised interest rates for the fourth time since October, a central bank official told traders the bank was straining to contain money pouring in from capital inflows, maturing central bank bills and bond repurchase agreements (repos).
As such, the central bank hopes Chinese banks can buy more of central bank bills and repos, traders who attended the meeting quoted the official as saying.
The central bank had held the meeting with primary dealers in its open market operations to discuss the nature of the operations in the year ahead.
At the meeting, an official said the inflation outlook was "not optimistic", making this year's credit controls a difficult task, traders who attended the meeting said.
The official added that China needed to consider the policy changes of foreign central banks when setting its monetary policy, traders said.
Excess cash is among drivers of China's inflation and is a worry for the government as rising prices have stirred social unrest in the past.
To drain the economy of a surfeit of cash, the central bank has leaned on raising interest rates and banks' reserve requirement ratio, as well as selling central bank bills and bonds repurchase agreements.
But some of its efforts are being undone by maturing bills and repos. In April alone, a total of 870 billion yuan ($133 billion) worth of bills and repos are maturing.
The central bank's efforts to sell bills are not always smooth.
Sales flopped at the start of the year after commercial banks, betting on rate rises, refused to step in as buyers in the hope of holding out for better returns when rates go up.
The central bank's dour outlook on prices echoes that of a prominent Chinese newspaper.
The official China Securities Journal said on Wednesday China's inflation could run at its fastest in over two years in coming months by topping 6 percent, keeping up the need for further policy tightening.
"There is still room for interest rates, the reserve requirement ratio and the exchange rate to move higher," the newspaper said in a front-page editorial
"It's unlikely that monetary policy will be loosened in the second quarter or even over a longer period of time."
The paper said the consumer price index will likely stay above 5 percent and perhaps quicken to an annual pace of 6 percent in the second quarter.
To get a handle over price pressures, it said China might allow the yuan to rise more than 5 percent this year.
The prediction seemed to ring true on Wednesday. The yuan hit a record peak against the dollar after the central bank guided the Chinese currency to an all-time high. ($1 = 6.542 Chinese yuan) (Reporting by Reuters China bureaux; Writing by Koh Gui Qing; Editing by Jacqueline Wong)