UK representatives will stop attending EU meetings from September 1, in order to focus on future relationships with the European Union and other nations, the Brexit Department said.
From that date UK representatives only attend EU meetings where the UK has a significant national interest in discussions, such as on security.
The Brexit Department claimed it makes sense to "unshackle" officials from EU meetings "to enable them to better focus their talents on our immediate national priorities".
The decision to cease attendance was made due to the fact that "many of the discussions in EU meetings will be about the future of the Union after the UK has left" and because the Brexit deadline is "very close".
Brexit Secretary Stephen Barclay said: "From now on we will only go to the meetings that really matter, reducing attendance by over half and saving hundreds of hours.
"This will free up time for ministers and their officials to get on with preparing for our departure on October 31 and seizing the opportunities that lie ahead."
Mr Tusk instead suggested the prime minister is actually supporting the return of a hard border by not proposing a realistic alternative.