The American Federation of Government Employees (AFGE) has demanded the release of all US government workers who were injured during a terrorist attack on the US Capitol last week, a day after they were released from the hospital.

The strike has led to a sharp increase in hospital closures in the US.

The AFGE has been campaigning for a one-year extension of the federal government’s $787 billion health care contract, which expired at the end of June.US President Donald Trump has said the attack was “justified” and “prevented an attack”, and that he was prepared to “deal with it”.

A report published by the Government Accountability Office (GAO) last week said that about 4,000 federal employees had been injured and that the cost of treating the injuries was at least $40bn.

On Tuesday, US Senator Debbie Stabenow, the ranking Democrat on the Senate Foreign Relations Committee, wrote to US Health Secretary Tom Price demanding an apology from the federal employees for their treatment.

“As members of the American public, we demand an immediate and unconditional apology from your department for the injuries to US government employees who were caught in the crossfire of the attack,” she said.

“These injuries, which have been described by US officials as ‘the costliest terrorist attack ever’ could have been prevented by better communication and coordination between US and local officials, and the swift response of federal authorities to the incident,” she added.

The US Capitol attack left four people dead and 20 injured, including US Representative Frederica Wilson, the wife of Representative Steve Scalise, a Republican.