The Australian arm of Ashurst is making back payments to some junior staff after a review last year revealed they had been underpaid, it has announced.

The firm undertook a review of all payments it made to staff covered by minimum wage requirements for the legal services sector and compared the pay with hours worked.

"Following the review, we identified a number of staff who were owed additional payments," Ashurst head of human resources Richard Knox said in a statement.

"As soon as we were made aware of the additional payments owed to staff, we acted to ensure all necessary adjustments were made to current and former staff affected, including interest, superannuation and leave balances adjusted where applicable. This process is almost complete," Knox said.

"We have made the necessary changes to ensure, moving forward, all payments owed to our staff for work performed are properly accounted for and made on time."

The review encompassed staff including law graduates who have not yet been admitted to practice.

The underpayment came about as some of the staff worked long hours, particularly during the government-initiated Royal Commission into misconduct by banks and other financial institutions, which reduced the hourly pay rate for those staff.

Several other law firms in Australia have undertaken or are undertaking reviews into staff pay.