Leeds General Infirmary has suspended surgery on children with congenital heart defects, a day after a high court judge ruled it could carry on performing such operations.

The hospital, which has been rocked by a long-running row over its children's heart services, said it had temporarily stopped carrying out the operations to allow an internal review to take place.

The Leeds Teaching Hospitals NHS trust will now contact parents directly and children who were being treated at Leeds will now be sent to other hospitals around England.

The surprise immediate decision had been taken because of "disturbing" warnings from surgeons, said the medical director of the NHS, Bruce Keogh, who called it "a highly responsible precautionary step". There has been a long-standing dispute about the number of deaths at the hospital.

"There have been rumblings in the cardiac surgical community for some time that all was not well in Leeds," Keogh told BBC Radio 4's Today programme. "On Tuesday I had two phone calls which I found disturbing, both from highly respected, temperate surgeons who commenced the conversations by saying they had to speak out."

One surgeon was concerned about the referrals process at the hospital, while the other was worried about staffing levels, he said. Preliminary data revealed this week shows mortality in the hospital's child congenital heart surgery unit was around twice the national average.

"I couldn't do nothing. I was really disturbed about the timing of this. I couldn't sit back just because the timing was inconvenient, awkward or would look suspicious, as it does," Keogh said.

The Leeds unit had been earmarked for closure by an NHS review, to concentrate children's heart surgery in fewer bigger centres, but on Wednesday a high court judge quashed the decision to shut it down, to the jubilation of campaigners.

Stuart Andrew, Conservative MP for Pudsey, who has led a cross-party campaign to keep the unit open, said he had not received one complaint about care. "I think it is very odd indeed. On Wednesday we had jubilation in the area because we found out that the high court supported everything we said, that actually the decision to close Leeds was based on information that wasn't used properly," he said. "We have always been told it's safe at Leeds. Suddenly that's changed."

Keogh and senior managers from the Care Quality Commission visited the hospital on Thursday to say it must stop all children's heart surgery there immediately. The review is expected to take three weeks.

Anne Keatley Clarke, chief executive of charity the Children's Heart Federation, wrote to the Care Quality Commission two and a half years ago to raise concerns about death rates, following up complaints with concerns about the difficulties parents were facing getting referrals in February.

"Heart surgery can be very, very complex. The surgeons are working with quite vulnerable children and therefore the outcomes can't be guaranteed and often children, although their lives will be saved, may well end up with some level of learning disability or delay," she told Today. "And the feeling was, although it was a feeling, that that might be happening more in the Leeds area than elsewhere."

Maggie Boyle, chief executive of the Leeds Teaching Hospitals trust, apologised on Thursday night to affected parents and families and assured them patient safety was being put first.

The decision has left many who campaigned to keep the unit open angry and confused. "We're mystified," said Sharon Cheng, from the Save Our Surgery group which is co-ordinating the fight to keep children's heart surgery in Leeds. "We don't know of anything that could justify this step."

More than 600,000 people, including parents concerned at having to travel long distances for their children's care, signed a petition to keep the Leeds unit open after the NHS review said surgery should stop at hospitals in Leeds, Leicester and London to focus care at fewer, larger sites, to concentrate medical expertise.

The leader of Leeds city council, Keith Wakefield, said he was "shocked at the timing of today's events". Greg Mulholland, MP for Leeds North West, called for Keogh to resign. In a statement on his website, Mulholland wrote: "To have arrived in Leeds and done this, without warning, just one day after the decision to close the Leeds unit was proved in a court of law to have been unlawful beggars belief. I believe that Sir Bruce Keogh should resign as he has both authorised this wholly unreasonable and deeply questionable action and also presided over the fundamentally flawed Safe and Sustainable review, which has proved an exercise in how not to effect major change to the NHS."