"We are obviously especially delighted but, for now, Chris remains a Northampton player. Out of respect for Saints, Saracens will not make any further comment on the matter," said a Saracens spokesman.
Ashton, who has scored 15 tries in 18 internationals for England, helped Saints reach the Heineken Cup final last season. To date he has scored 90 tries in 105 games for the club.
This weekend Northampton host unbeaten Munster in the final game in Pool 1 in Milton Keynes. They still have a mathematical chance of reaching the quarter-finals of either the Heineken Cup or Amlin Challenge Cup, but must win to stay in Europe.