The UK and EU could team up to strike international trade deals together after Brexit, Labour's shadow foreign secretary Emily Thornberry has said.
Ms Thornberry insisted Labour wanted to negotiate a withdrawal deal with Brussels that would see a new customs union which would "look pretty much like" the current one.
The senior shadow cabinet figure suggested Britain could work with Brussels in drawing up trade deals with outside countries after Brexit, rather than the UK making such agreements on its own.
Ms Thornberry told LBC: "If we were, during these negotiations, to say to the European Union, if you want to negotiate with third parties, with third countries, we could be connected to that agreement, and it would be to the advantage of Europe that you have a great big economy like Britain as part of your negotiations.
"But, we will need to be part of forming those relationships and forming those rules in order for you to take advantage of the fact that you are negotiating on behalf of Europe and you're negotiating with us too."
Ms Thornberry denied such a move would replicate the current situation.
"It is not the same as now because at the moment the European Union negotiates deals with the third parties, we would need to play a part in forming those rules.
"We would need to make sure that any deal that was done with third countries would be in our interest, not contrary to our interest."
The shadow foreign secretary insisted a "form of customs union" was needed after Brexit.
"Technically, because we are leaving the European Union we can't be in the customs union that we are in now.
"So, we leave and then we have to negotiate a new agreement. That we think is likely to be a customs union that will look pretty much like the current customs union.
"We cannot see how you will have anything other than a hard border in Ireland if we are not in a customs union."
The intervention comes after it emerged that Jeremy Corbyn will make a significant speech on Brexit policy on Monday.
Mr Corbyn has come under pressure from Labour MPs to provide clarity on his stance on membership of the single market and customs union, and a spokesman said on Wednesday that his thinking on the issue was "evolving and deepening".
Shadow chancellor John McDonnell has made it clear that remaining in the single market would leave many voters feeling the referendum result had been ignored.