The EU is preparing legal proceedings against AstraZeneca, according to Reuters sources.
That after the drugmaker cut supplies of vaccines to the bloc.
The move would mark a further step in EU plans to sever ties with the Anglo-Swedish firm.
Brussels has been angered by AstraZeneca's repeated cuts to supplies.
The reductions have contributed to major delays in Europe's vaccine rollout.
News of the possible \legal action was first reported by Politico.
It says a majority of EU states support suing AstraZeneca.
There was no immediate comment from the European Commission or the company.
AstraZeneca had said it aimed to deliver 300 million doses of its vaccine by June.
But in March it said it would only be able to deliver a third of that amount.
That same month saw the EU send a letter to the firm, marking the first step in legal proceedings.