Britain will only host one Diamond League meeting in 2021 in what sprint hurdler Andrew Pozzi described as "a huge step backwards".
London will stage the event on July 13, less than two weeks before the start of the Tokyo Olympics, while Gateshead has been dropped from the programme.
Pozzi, the current world indoor champion over 60 metres, wrote on Twitter: "Having only one UK Diamond League in 2021 feels like a huge step backwards for the sport in our country.
"Athletics in the UK is facing many challenges, but I fear reducing its top offering to a single Tuesday night will only add to them."
Fourteen meetings have been scheduled, although organisers stressed the calendar is provisional depending on developments in the coronavirus pandemic.
The series will begin in Rabat, Morocco on May 23 and conclude in Zurich on September 8 and 9.
