Fashion firms Asos and Primark have announced new sustainability commitments, with both saying they will keep prices affordable.

Asos says it is aiming to achieve a net-zero impact on the environment by 2030.

Primark says its clothes will be made using recycled or "more sustainably sourced materials" by the same date.

The budget retailer has also promised to halve carbon emissions across its operations.

Critics warned, however, that these goals will be hard to track as fast-fashion supply chains often lack transparency.

 Asos set out new environmental and social targets. They include:

•          Reducing carbon emissions generated by its clothes production and deliveries
•          Ensuring all of its own-brand products are made from sustainable or recycled materials by 2030
•          Giving customers more information on its supply chain
•          Recruiting a more diverse workforce, including 50% female representation across its leadership team

In a statement, Primark also said it would design its clothes to be more durable so they can be recycled and last longer - without increasing its prices.

It said it would "pursue a living wage for workers in its supply chain", but did not specify how much this wage would be in the countries where it has employees or when this would happen. Primark has 397 stores across 14 countries and employs about 70,000 people.