LONDON (AP) — Britain’s antitrust watchdog said Monday that it is escalating its investigation of plans by Getty Images to buy rival Shutterstock, stepping up scrutiny of the $3.7 billion deal that would create a visual content giant.

The Competition and Markets Authority said that it was opening an in-depth merger investigation after its preliminary inquiry raised concerns that the deal would result in higher prices, worse commercial terms, or lower quality of editorial and stock images.

The proposed merger was announced in January with companies that make money from still images created by humans face increasing competition from those generated by artificial intelligence.

The CMA said it was taking a closer look after its initial inquiry found that the combination of the two U.S. companies might “result in a substantial lessening of competition within a market or markets in the United Kingdom.”

Getty said it’s “disappointed” but “remains committed” to the deal and will continue to work with regulators and with Shutterstock to secure approval.

Both companies license content including photos, illustrations, music and videos to major British media companies, advertisers, publishers and designers, as well as small and medium businesses in the creative industry, the CMA said.

After businesses and trade groups voiced concerns to the CMA during the preliminary inquiry about the supply of editorial and stock content, Getty and Shutterstock responded with a “complex package of remedies,” according to the British regulator. The watchdog escalates its investigation because the offers didn’t “fully address” the concerns.

Shutterstock said Monday that Getty offered “comprehensive remedies” to avert further review, but that it too, remains committed to the merger.

The CMA has until April 16 to make a final decision on the deal, which it said the U.S. Department of Justice was also reviewing. The watchdog could decide to either clear the transaction, or impose its own remedies, including selling off parts of the business or blocking it.