London, Mar 25 (IANS): UK Health Secretary Matt Hancock said on Thursday the country has an "exclusive" contract with coronavirus vaccine developer AstraZeneca, while the European Union's is based on a "best efforts" basis.

Hancock told the Financial Times that both sides were looking to resolve a dispute surrounding vaccine delivery, reports dpa news agency.

But he added the bloc should not try and suspend the export of vaccines from a site in the Netherlands to the UK, due to the nature of the contractual agreements they have with the British-Swedish pharmaceutical giant.

"I believe that free trading nations follow the law of contracts," he told the newspaper on Thursday.

"They have a 'best efforts' contract and we have an exclusivity deal.

"Our contract trumps theirs. It's called contract law — it's very straightforward," Hancock added.

On Wednesday, the EU tightened controls of its vaccine exports further, allowing shipments headed almost anywhere to be halted.

The move triggered warnings from the UK, a major recipient of EU-produced jabs.

Member states including Belgium and Ireland have voiced concern about the potential backlash to blockades.

The UK and the EU also issued a joint statement on Wednesday evening, stating they were working on a "win-win situation" to "expand vaccine supply for all our citizens".