BMW has warned investors that it was suffering higher costs in developing electric vehicles, sending its shares down by more than 6pc.

The carmaker also reported a lower profit margin for the three months to the end of June, which disappointed investors.

It is stocking up on parts anticipating an improvement in deliveries, which hit profitability and cash flow, it said.

The announcement was made in advance of its full earnings, due on Thursday. Investors will look for more detail on how BMW expects to improve its finances through the rest of the year, where it expects an improvement in its margins.

“BMW Group expects higher expenses for suppliers due to inflation and the supply chain to continue to be a headwind in the second half of the year,” it said.

Cash flow would be hit by an “increase in inventory to build product supply pipeline, and higher material and raw material costs,” it added.

Rival Mercedes has already suggested that a boom in its top-end models, which are highly profitable, may be cooling as more customers opt for its lower-margin middle-market vehicles. A similar shift could also hit BMW.