Adds details in paragraphs 2-5

June 12 (Reuters) - The Commodity Futures Trading Commission, the top U.S. derivatives regulator, is considering whether to block CME Group's CME.O bid to launch a round-the-clock oil contract, Bloomberg News reported on Friday, citing an official familiar with the matter.

CME Group, the world's leading derivatives marketplace, had announced on Thursday that it would offer 24/7 trading in some crude and gold futures contracts, pending regulatory review.

The new oil-linked contract, which would be one-tenth the size of the existing Micro WTI futures contract, is slated for release on August 30, according to the report.

The exchange wants to start round-the-clock trading in 1-ounce gold futures on July 26, the Bloomberg report said.

CME Group did not immediately respond to a Reuters request for comment.