The competition regulator has raised concerns that the planned $2 billion takeover of pay TV operator Austar by rival Foxtel, part owned by Rupert Murdoch's News Corp, could hurt competition on three fronts.

The Australian Competition and Consumer Commission today delayed its decision on Foxtel's bid until September, indicating it sees problems in it proceeding at all.

The ACCC said it has a preliminary view it would substantially lessen competition in pay TV, the market for buying programs and that for the supply of telecommunications products because it is half owned by Telstra.

Austar, meanwhile, said the company remained committed to the Foxtel deal, and would work with regulators to resolve the issues.

The comments helped Austar shares pare some of their earlier losses, although they ended the day off 21 cents, or 16 per cent, at $1.085. Earlier, they were as much as 20 per cent lower, trimming the company's stock value to about $1.35 billion.