Aldi and Lidl could soon be covered by the same land agreement rules as the UK’s largest supermarket chains.

A proposal by the Competition and Markets Authority (CMA) would prevent the German discount brands from blocking rival supermarkets from opening outlets close to their stores.

The rules designed to stop large grocery retailers from using land agreements to make it harder for rival supermarkets to open nearby, particularly through restrictive covenants and exclusivity arrangements, were first introduced in 2010.

The restrictions currently apply to seven retailers including Asda, Co‑op, Marks & Spencer, Morrisons, Sainsbury’s, Tesco and Waitrose.

In a provisional decision, the CMA said it believes Aldi, Lidl GB and Lidl NI should also be subject to the rules.

The regulator said the brands were not originally included in the rules due to their more limited range of products, but said they should now be covered by the restrictions after expanding their shop estate and opening larger stores.

Aldi is the UK’s fourth largest grocer, with a 10.8 per cent share of the market, and Lidl the sixth largest with an 8.8 per cent share, according to recent figures from Worldpanel.

Both companies have rapidly expanded through store openings in recent years, while they have also attracted new shoppers through their discount pricing.

The CMA has said it is seeking further views before reaching a final decision.

Juliette Enser, CMA executive director of competition enforcement and markets, said: “We want everyone to have the best choice of supermarket and range of prices when buying their groceries.

“To ensure this happens, we put rules in place to prevent big supermarket chains blocking rival stores from opening nearby – and now we propose applying those rules to Aldi and Lidl too.

“This is about allowing shoppers to choose where they spend their money and levelling the playing field for all major supermarkets. Today’s proposals are provisional and we welcome views before deciding the best way forward.”

An Aldi spokesperson said: “The CMA’s provisional decision does not impact our long-term growth plans across the UK.

“We remain firmly committed to opening hundreds of new stores across the country, bringing Aldi’s unbeatable value and award-winning quality to even more customers.”

Lidl has been contacted for comment.