New DLR trains are unlikely to enter service until the end of this year.

Under the plans initially put forward by Transport for London (TfL), the first of the 54 walk-through trains would have already been carrying passengers.

But TfL said that it had encountered “some complex challenges” during testing, delaying the rollout of the new trains.

The new fleet is set to replace 33 of the oldest trains used on the DLR, with the remainder used to help boost capacity on the network.

TfL has confirmed that it still hopes to introduce some of the new trains by the end of this year, with the entirety of the fleet in operation by 2026.

The walk-through design of the trains will increase capacity on each train by 10%.

The trains will also feature the latest audio and visual real time travel information, air conditioning and mobile device charge points.

TfL claims the new trains will provide better facilities for those with mobility impairments with three multi-use areas and three dedicated wheelchair spaces.

Arran Rusling, TfL’s Head of Programme for DLR Rolling Stock Replacement, said: “Our programme of rigorous testing continues of the new DLR fleet to ensure the trains can enter service safely and reliably.

“As part of this we encountered some complex challenges, which means we will introduce the new trains into passenger service later this year.

“We are still on track to introduce all 54 of these new trains in passenger service by 2026, delivering a range of customer benefits including improved reliability and increased capacity across the DLR network.”