Jo Johnson, who like his brother is a Conservative MP, will tonight urge businesses to fight against a "fanciful Brexit bluster".
Speaking to an audience of businesses and academics, the universities and science minister will say: “If we want Britain to remain as a global innovation hub, then we’ve all got to play our part.”
His brother, the current London mayor, is one of the most high-profile backers of the campaign for a so-called Brexit.
Johnson will describe London as a "fabulous melting pot – thanks in no small part to the way bright people from around the EU can come here and set up businesses in a vibrant pro-enterprise environment, where there’s ready access to pretty much limitless finance and talent".
He will say: “We’ve got a huge competitive advantage in Europe – the best of both worlds. But as the referendum approaches, the question is whether we are going to keep hold of the qualities that help give us this edge.”
Johnson will say a large part of Britain's success in innovation is its “openness to our nearest neighbours and to the world”.
“Our membership of the EU guarantees the freedom to invest and collaborate across a single market of more than 500m people,” he will say.
Johnson will add: “Are we going to preserve the factors that have created a great tech cluster, or succumb to fanciful Brexit bluster?
“Do we want to fuel our knowledge economy with science and innovation, or fill it up with piffle and ventilation?
“So let’s celebrate Britain’s success as a global innovation hub – and make sure we keep hold of that title for years to come.”