An executive of Japanese tech firm Fujitsu says the company knew from the very start that its accounting system used at British Post Office was flawed.

The admission came in a public inquiry led by an independent panel of the British government that has been looking into the Post Office accounting scandal.

From 1999 to 2015, more than 700 post office workers, including branch managers, were prosecuted for embezzlement and other charges after gaps were found between cash at the counter and records on Fujitsu's accounting system called Horizon.

In 2019, a UK court ruled for a group of postal managers who filed a lawsuit claiming the system was flawed.

Paul Patterson, who heads Fujitsu's Europe operations, testified on Friday at the public hearing.

He said there were bugs, errors and defects, which were well known to all parties from the very start.

He admitted that the problem had been left unaddressed for nearly 20 years from November 1999, when the system was introduced, to 2018.

Patterson said Fujitsu let society and post office operators down, adding that the company intends to contribute to a fund to compensate those who were wrongly prosecuted.

The government panel is expected to clarify why hundreds of people were prosecuted as Fujitsu was aware of the accounting system's flaws.