He justified the decision by saying that Ukraine could not afford to break trade ties with Russia.
The EU agreement was to have been signed Friday and since then the protests have gained strength.
Sunday's demonstration also was energized by anger over the violent dispersal of several hundred protesters at Independence Square early Saturday.
Some of the protesters were bleeding from their heads and arms after riot police beat them with truncheons.
As the vast column of demonstrators approached the square on Sunday and removed metal barriers blocking it off, all police left the square.
