Tusk made the announcement after meeting UK Prime Minister Keir Starmer on the sidelines of the European Political Community summit in Yerevan, Armenia, on Monday.
"It will be a treaty that meaningfully strengthens our cooperation, particularly in the field of defence," Tusk said, adding that the UK was a partner with significant potential for sustained military cooperation.
He also said London was keen to have Poland as a reliable advocate for closer UK-EU ties, noting that a clear majority of people in Britain now regret Brexit and want stronger relations with the European Union.
Polish PM to visit Canada
On the same sidelines, Tusk met Canadian Prime Minister Mark Carney, the first non-European leader to attend the EPC summit, and announced he would travel to Canada to finalise a range of bilateral agreements.
The two leaders agreed to deepen cooperation in defence, nuclear and renewable energy, and intelligence services.
Tusk said he had jokingly expressed support for the idea of Canada joining the EU, and indicated he was open to developing a format bringing Canada, Norway and the UK closer to the bloc.
He stressed, however, this would not be an alternative to European-American relations.
(ał)
Source: PAP