The two British firms with rich motorsport heritage had been collaborating on what is claimed to be the world most powerful production car.
A spokesperson for the Geely-owned manufacturer told CarAdvice: "As the Evija programme enters its latter stages, Lotus has elected to bring the project in house due to delivery problems from WAE."
The Williams division declined to comment directly on the matter when approached by CarAdvice, however it forwarded a statement claiming the decision is "wrongful, without any legal basis, and made for Lotus and Geely’s unrelated commercial reasons.
"In particular, WAE is firmly of the view that the allegations - including so called “delivery problems” - of breach of the agreement made by Lotus are false and contrived," the statement continued.
"WAE has been left with no choice but to instigate legal action to pursue compensation for unpaid invoices, none of which have been paid since April 2020, and other losses caused by Lotus’ breach of the agreement."
Above: the all-electric Evija hypercar.
The partnership was announced in early 2019, however, earlier this year the Williams Formula One team – and its minority stake in WAE – were sold to little-known New York investment firm BCE Limited.
It has been speculated that Lotus's parent company Geely may be in dispute with the tech firm’s secretive new shareholders, however Lotus's spokesperson told CarAdvice this is not the case.
The Evija launch was recently pushed back by at least five months because of the coronavirus pandemic.
It will now likely be unveiled mid-2021.
The £1.7 million (approximately AU$3.1 million) vehicle is powered by four electric motors, which draw voltage from a 70kWh lithium-ion battery.
It produces 1470kW/1700Nm, and has a range of approximately 400km.
Earlier this year CarAdvice reported that Australian deliveries may be delayed due to a range of compliance hurdles.