ILMN Illumina Inc

U.S. regulators have asked Roche Holding AG (ROG.VX, RHHBY) for additional information about its proposed takeover of Illumina Inc. (ILMN), the drug maker said Tuesday.

The Federal Trade Commission's request reflects antitrust concerns about Roche's microarray business and would delay any acquisition another 10 days after Roche complies with the second request under U.S. law.

Roche is still working to complete its hostile takeover of Illumina, which continues to oppose the Swiss company's offer as inadequate. Illumina makes machines that use blood or tissue samples to decode a person's entire genetic makeup in about a week--a process known as DNA sequencing.

Shares of the takeover target closed at $50.34 Tuesday and were unchanged after hours. Roche's cash offer values the company at $44.50 a share.

-By Drew FitzGerald, Dow Jones Newswires; 212-416-2909; Andrew.FitzGerald@dowjones.com