JOHANESBURG, May 3 (Reuters) - Impala Platinum's (IMPJ.J) Zimbabwe unit Zimplats Holdings (ZIM.AX) said on Monday 3 May metal output in concentrate fell to 93,845 ounces in the third quarter, but profits rose 14 percent on firmer metal prices.

Zimplats, majority owned by South Africa's Implats -- the world's No. 2 platinum producer -- said operating profit rose 14 percent to $57 million in the March quarter compared with the December quarter.

The company produced 94,670 ounces in the December quarter.

The company said metal prices continued an upward trend in the quarter in line with the global economic recovery and also increased investor interest in platinum group metals.

Zimplats said revenue for the quarter was 9 percent higher than the preceding quarter, reflecting the increased sales volumes and improved metal prices.

Operating costs rose 4 percent in line with the sales.

The company said it would go ahead with its Ngezi phase II expansion project estimated to cost $445 million.

The expansion of the mine will lift annual platinum output to 270,000 ounces from 180,000 ounces.

Completion of the project will depend on among other things, compliance of Zimbabwe's proposed indigenisation laws and an agreement with the government on the $34 million the company is owed by the Reserve Bank of Zimbabwe.

Zimplats said the development of Bimha Mine remained on course for completion by May 2011. (Reporting by Shapi Shacinda)