New controls to curb the National Health Service's agency staff bills have saved £300 million since their introduction last October.

According to figures released by NHS Improvement, the health service was on track to spend some £4 billion on agency staff for the financial year 2015/16, but new restrictions have helped pull this down to £3.7 billion.

The measures to reduce the money spent on agency workers, and encourage staff back into full time employment, include capping the rates that can be paid for individual shifts. NHS Improvement noted that its latest analysis shows that the average price paid for a nursing shift has now dropped by 10%.

Some providers have themselves also taken extra steps to cut back on this spend, such as Hounslow and Richmond Community Healthcare NHS Trust, which has reduced price cap overrides by 80%, and Oxford University Hospitals NHS Foundation Trust, which has introduced an online tool to improve visibility of bank and agency staff usage.

"The measures have had a real impact and we are starting to see a significant reduction in the amount of NHS money being paid to these agencies," said the group's chief executive Jim Mackey. "We need to keep up the pressure and make sure the era of overreliance on agency staff comes to an end."

He also told the Health Services Journal that there are still some trusts "that simply aren't doing enough to reduce their spending on agency staff", and stressed that dramatically reducing this cash bleed is "a key part of our plan to balance the books".

"For too long rip off staffing agencies have been able to charge extortionate rates, but this data shows our controls are bearing fruit", noted Health Secretary Jeremy Hunt.

"This is good news for patients because the savings will be reinvested in frontline patient care and it will also lead to more staff coming back from agencies to permanent roles in the NHS, enabling hospitals to deliver better continuity of care."

NHS Improvement previously said the clampdown could remove £1 billion from the agency staffing bill by 2018.