Boris Johnson will demand that the increasingly isolated French president, Emmanuel Macron, caves in to UK demands on fishing as the price for a trade and security deal at a key meeting with the European commission president on Saturday.

The prime minister will feel strengthened by comments from the German chancellor, Angela Merkel, on Friday, when she described the fisheries deal struck by Britain with Norway this week as a “constructive indicator”.

British officials argue that Norway, a non-EU member state, which conducts annual negotiations with the bloc on fishing quotas, should be the model for a post-Brexit deal on shared stocks.

“I don’t think that’s a bad message at all for us, I think it is rather one that shows that one can find ways to come to an agreement,” Merkel said of the agreement between London and Oslo.

Johnson will speak to the European commission president, Ursula von der Leyen, on Saturday afternoon in a video-conference call to “take stock of negotiations and discuss next steps”.

Von der Leyen warned on Friday that most contentious issues, including fisheries and the control of domestic subsidies, remained “completely open”. The EU now expects a deal to materialise only in late October or early November.

But in a statement, the UK’s chief negotiator, David Frost, suggested there had been movement on the issue of state aid.

He made his strongest comments on access to British waters for European fishing fleet, an issue where the EU has been internally split in recent weeks.