A full review is underway into the problems that third rail electro-magnetic interference is causing for the computer software being used to run Island Line's new trains - with no firm date for the network's return.

Operator South Western Railway (SWR) says testing has revealed 'inconsistent behaviours' on its rolling stock and says, despite 'dozens of attempts' by the software designer to fix the issue with patches, a 'thorough review of the code, to get to the root of the problem,' is now underway.

The interference issue is also known as arcing.

Island Line closed in January, for a £26 million upgrade including newly refurbished trains, platform improvements and a new passing point, to allow more frequent services.

It was originally due to reopen in March, before the date was pushed back.

The start date has now been pushed back for a second time and it is unknown when the network will reopen, or if it will be back for what is expected to be a busy summer season, at the end of the government's roadmap out of Covid-19 lockdown.

On behalf of SWR, Vivarail is fitting out and refurbishing rolling stock to replace the old 1923 tube trains.

It is working with the software developer to try to fix the issue.

Replacement buses have been serving the route since Island Line closed.

SWR says it will double capacity from May 17 - to match the expected rail timetable.

Only one new Vivarail train has arrived on the Isle of Wight, which the County Press covered earlier this year.

An SWR spokesperson said: "The safety and reliability of our service remains the number one priority for South Western Railway and Vivarail."

"Regrettably that leads to uncertainty in the project timeline."

"We will provide further updates on that programme in due course. We are working incredibly hard to reopen a safe, reliable and fully upgraded Island Line as soon as possible.

The franchisee said the main reason for the delay was because delivery of the new trains had been held up and has previously said that Covid-19 was causing delays.