Defence Secretary Ben Wallace has warned any bid by the EU to block coronavirus vaccine exports to the UK would be "counterproductive" and damage the bloc's reputation globally.
He made his comments as EU Commissioner Mairead McGuinness refused to rule out a ban, saying that "everything is on the table".
European Commission president Ursula von der Leyen has insisted the EU has the power to "forbid" exports of coronavirus doses.
The war of words comes amid growing frustration in Brussels that the EU is not getting the supplies it expected of the AstraZeneca COVID-19 vaccine from the British-Swedish manufacturer.
The bloc has been locked in a dispute with the pharmaceutical giant, which saw it briefly override part of the Brexit deal on Northern Ireland to impose export controls on jabs, triggering an angry backlash and swift U-turn.
Many European countries are experiencing a surge in infections amid the slow vaccine rollout, with France and Italy among those forced into new restrictions.
Speaking on Sky News's Sophy Ridge On Sunday programme, Mr Wallace said the EU would suffer "reputational" damage if it tried interfering with vaccine exports.
He said: "If contracts and undertakings get broken, that is a very damaging thing to happen for a trading bloc which prides itself on the rule of law.
"It would be counterproductive because the one thing we know about vaccine production and manufacturing is that it is collaborative.
"If we start to unpick that, if the Commission were to start to do that, I think they would undermine not only their citizens' chances of having a proper vaccine programme, but also many other countries around the world with the reputational damage to the EU, I think, they would find very hard to change over the short-term."
Ms McGuinness said no decisions had been taken but EU leaders would consider the matter when they meet on Thursday.
Speaking to The Andrew Marr Show on the BBC, she said: "European citizens are growing angry and upset at the fact that the vaccine rollout has not happened as rapidly as we had anticipated
"Both the EU and the UK have contracts with AstraZeneca and my understanding is the company is supplying the UK but not the European Union.
"We are supplying the UK with other vaccines, so I think this is just about openness and transparency."
She added: "The leaders will meet this week and they will make an assessment of the current situation about the rollout of vaccines and perhaps make decisions.
"As the president of the commission said herself, everything is on the table but there is no decision."
Analysis: Minister hints at retaliation if EU impose vaccine export ban
By Rob Powell, political correspondent
He didn't say it explicitly, but Ben Wallace is clearly hinting that the UK could retaliate if the EU decided to block vaccine exports.
Any kind of cross-border jab war would not be good for either side because the supply chains are so interdependent.
For example, if the EU blocked shipments of the Pfizer vaccine going to the UK, Westminster may respond by stopping the Yorkshire-made lipids that are needed for the jab going over to Belgium.
But the European Commission is under immense pressure from member states.
A combination of over-caution regarding the Oxford jab and stuttering supplies from AstraZeneca has seen the bloc's vaccine rollout get off to a sluggish start.
Brussels chief Ursula von der Leyen raised the temperature further by pointedly mentioning that no vaccine stocks had come from the UK recently.
European leaders will meet on Thursday to discuss the way forward.
Set against febrile Brexit situation, a ban on exports to the UK would be an major step, especially given apparent reassurances Boris Johnson extracted from the EU earlier this year.