Boris Johnson will speak to the German chancellor, Angela Merkel, president Emmanuel Macron of France and the European commission president, Jean-Claude Juncker, by the end of Monday to urge them to support his Brexit deal, the Sunday Times has reported.

Johnson will offer the three leaders the option to either help him deliver a new deal this week or agree on a “friendly version” of a no-deal Brexit by 31 October, the newspaper said, citing a source familiar with the conversations.

“He’ll be talking to Merkel, Macron and Juncker by the end of Monday to see if there’s agreement on a landing zone for Northern Ireland and customs,” the source was quoted as telling the newspaper. “The alternative is to agree a friendly version of no deal and finish it that way.”

Security chiefs have convinced Johnson a no-deal Brexit will heighten the danger of extremist attacks in Northern Ireland and on the mainland, along with sectarian violence in cities such as Glasgow, according to the report.

As a result Johnson desperately wanted a Brexit deal, the Sunday Times reported.

“Any one of these risks we could cope with, but taken collectively they would be a massive challenge to the UK state and no one would choose to go down that route,” Johnson told a senior Conservative in a private conversation, according to the newspaper.

A European Union source cited by the Sunday Times said the chances of a deal at Thursday’s EU summit in Brussels were “50-50”. On Friday, Johnson declined to say whether Northern Ireland would stay in the EU customs union after Brexit.