Badly-needed works to refurbish Jubilee Line trains are now under way, Sadiq Khan has said, two months after services were cut back because of the number of breakdowns.

Services on the line were reduced from 30 trains per hour during peak time to 27 in May, resulting in longer waits for trains for the line’s 4.4 million weekly users.

Khan said in a written response to a question from Krupesh Hirani, a London Assembly member, that refurbishment work on the trains, which have been in service since 1997, had been delayed by the pandemic and “issues with suppliers”.

A £132 million programme to refurbish the fleet was now under way, Khan said, with seven of the 63 line’s trains already having been returned to service.

“By temporarily reducing the number of trains scheduled to run the timetable, TfL expects to offer a more reliable and evenly-spaced service, even though the scheduled gaps between trains are slightly longer,” Khan said.

“The temporary Jubilee line timetable means that TfL will run up to 27 trains per hour, instead of the 30 trains per hour currently scheduled at peak times. This equates to a train every 2.2 minutes.

“TfL is investing approximately £132 million in the overhaul of the Jubilee line fleet, with the first seven trains now complete. This work is already having an impact, with an improved performance on the Jubilee line in recent weeks.

“From June 2023, one train per week will be overhauled on the Jubilee line, with these works due to be completed by September 2024.”

The opening of the Elizabeth Line will have taken some pressure off the Jubilee Line over the past year, although many passengers at North Greenwich will now be using it as an alternative to Southeastern services that have been cut back by the Westminster government.

While the Jubilee Line’s trains, known as 1996 stock, are showing their age, there are far older carriages on the Tube network. The Bakerloo Line’s trains have been in service for more than 50 years, while Piccadilly Line trains have been rattling around since 1975.

Hirani, who represents Brent & Harrow for Labour, was kept waiting for nearly two months for his response. It was published today, eight weeks after he submitted his question on May 23.