The logo of Swiss drugmaker Roche is seen at its headquarters in Basel, Switzerland February 1, 2018. REUTERS/Arnd Wiegmann

ZURICH (Reuters) - Swiss drugmaker Roche’s $4.3 billion takeover of U.S. gene therapy specialist Spark Therapeutics has been pushed back again, possibly beyond the first half, as regulators continue to scrutinize the deal for its effect on competition.

Roche said on Monday that both companies received a request for more information from the U.S. Federal Trade Commission in connection with the FTC’s review of the deal, sending Spark shares down nearly 15% at $93 in premarket trading on Monday.

Roche also said that the UK Competition and Markets Authority (CMA) has opened an investigation.

Roche wants to buy Spark to, among other things, get a hold of U.S. firm’s experimental gene therapy for hemophilia A as well as its platform to develop other treatments for genetic diseases. But Roche has been forced to push back completion repeatedly, this time giving itself to July 31, beyond its self-imposed first-half deadline, to wrap things up.

“The parties remain committed to the transaction and are working cooperatively and expeditiously with the FTC in connection with its review,” Roche said in a statement.

The FTC has said it does not comment on cases it is reviewing.

The British regulator’s separate inquiry is aimed at determining whether the CMA considers it has jurisdiction over Roche’s acquisition, and if so, whether it could hurt competition in Britain.

“Pending the outcome of its investigation, the CMA has issued an Interim Enforcement Order that would become effective upon closing of the transaction and would require Roche to hold separate the Spark business,” Roche said. “The parties are working cooperatively with the CMA and will continue to do so.”