Harry Kane has not returned to the Tottenham training ground as expected on Monday morning amid speculation over his link with a move to Manchester City.
Kane was scheduled to have coronavirus testing on Monday before starting training on Tuesday.
He has had a three-week break after helping England reach the Euro 2020 final.
Spurs have offered no explanation for why the 28-year-old did not turn up.
It is understood Kane felt he had a gentleman’s agreement with Tottenham chairman Daniel Levy that he could leave the club this summer.
A pre-Euro 2020 move did not materialise as he hoped, but Manchester City remain keen on signing the England captain.
Kane’s international’s team-mate Jack Grealish is also a target for City, who have made a £100m bid for the Aston Villa midfielder, and he turned up for pre-season training with the Midlands club on Monday.
Kane’s contract with Spurs runs until 2024 after he signed a six-year deal in 2018.
He scored 23 top-flight goals last season to claim the Premier League golden boot for a third time, having previously won the award in 2015-16 and 2016-17.
He also has 221 Tottenham goals to his name, which puts him second in their all-time goalscorers’ list behind Jimmy Greaves, who scored 266 times for the club between 1961 and 1970.