JAKARTA, Aug 24 (Reuters) - Oil and gas giant Saudi Aramco may reduce its stake in the Cilacap refinery upgrade in Indonesia, which it plans to develop with Indonesian state energy company Pertamina , the country's energy minister said on Wednesday.

Aramco has requested to reduce its stake in the project to 30 percent from 45 percent, interim energy minister Luhut Pandjaitan told reporters.

"Aramco's progress has been rather slow. We want to chase this, not just talk. We want something concrete now," he added.

(Reporting by Wilda Asmarini; Writing by Fergus Jensen) ((fergus.jensen@thomsonreuters.com; +62 21 2992 7604; Reuters Messaging: fergus.jensen.thomsonreuters.com@reuters.net))