No WTA tournaments will be played until at least 2 May after the tour extended its suspension because of coronavirus.
The tour was initially on hold until 20 April but events in Stuttgart, Istanbul and Prague have now also been dropped.
The WTA says it will make a decision this week about the season's remaining European clay court tournaments in Madrid, Rome and Strasbourg.
It added it "will continue to monitor this situation closely and its impact on the 2020 WTA Tour season".