Advertising and marketing conglomerate Omnicom Group Inc (OMC.N) has recommended that clients pause their spending on Twitter in the short term, The Verge reported on Friday, citing an internal memo.

Omnicom serves over 5,000 clients in 70 countries, including McDonald's Corp (MCD.N), Apple (AAPL.O) and Johnson & Johnson (JNJ.N).

The move emphasizes a growing skepticism among agencies and brands about the micro-blogging site's future since Elon Musk took over the helm.

Omnicom did not immediately respond to a Reuters request for comment.

"The risk to our clients' brand safety has risen sharply to a level most would find unacceptable," the report added, citing the Omnicom memo.

Ad sales represented over 90% of Twitter's revenue in the second quarter.

Last month, U.S. automaker General Motors Co (GM.N) said it had temporarily halted paid advertising on Twitter.