Boris Johnson has raised the prospect of a second crossing for the English Channel after top-level talks between the UK and France.
The Foreign Secretary said "good connections" were important to the relationship between the two countries and wondered whether the Channel Tunnel should merely be regarded as "a first step".
Mr Johnson said the UK-France summit, attended by French President Emmanuel Macron and Prime Minister Theresa May, had agreed to establish a panel of experts to look at major projects.
The Foreign Secretary is understood to want a new fixed link between the UK and France and believes "it's crazy that two of the biggest economies in the world are connected by one railway line when they are only 20 miles apart".
But suggestions that the new link could come in the form of a bridge over the Channel won a sceptical response from representatives of UK shipping.
Trade body the UK Chamber of Shipping said in a tweet: "Building a huge concrete structure in the middle of the world's busiest shipping lane might come with some challenges."
Sources close to Mr Johnson said the French President was enthusiastic about the idea of a new link.
A joint declaration after the summit at the Royal Military Academy, Sandhurst, said: "The United Kingdom and France have a long history of collaboration in delivering cutting-edge technologies.
"Whether pioneering supersonic travel or better connecting our countries through the Channel Tunnel, co-operation between our nations has
produced radical innovation.
"We will continue to partner to invest in the technologies of tomorrow, including through a joint scheme, supported by up to 100,000 euro (£88,000) per year, to support academic exchanges, scientific collaboration, and innovation. "
The communique added: "As we look to the future of our relationship
through the 21st century, we have agreed to establish a joint group of eminent
and qualified persons to examine other options for future co-operation, including for significant projects."