Stokes and Alex Hales, who was with the Durham all-rounder last Sunday night, have been suspended indefinitely on full pay while the police investigate the incident.
Steven Finn will replace Stokes in the squad initially although “no final decision has been taken on his involvement in Australia”.
“England Selectors have added Steven Finn to the squad for the Ashes Tests, in light of the on-going investigation by Avon & Somerset Police, the Cricket Discipline Commission process and all other considerations,” an ECB statement said.
“Finn will travel to Australia with the England Test team for the full five-match Ashes series.”
England’s director of cricket Andrew Strauss said: “With the Ashes just around the corner, it’s important to give the players, the coaching staff and supporters some clarity around a complex situation.
“This decision will help us in the weeks ahead and give every player and the whole England set-up the best chance to focus on the challenge ahead in Australia.
“Steven is a high-quality cricketer, with considerable experience of both international cricket and Australian conditions.
“The selectors believe he will add to the range of options and the squad will be further supported by the arrival of the Lions in Australia in November.
“We have spoken to Ben and assured him that our decision in no way prejudges the outcome of the ongoing police investigation or Cricket Discipline Commission process, as can be seen by the award of Central Contracts.”
The list of central contracts was due to be released on Wednesday but was delayed by 48 hours in light of recent disciplinary problems.
According to an ECB statement, Jonny Bairstow, Jake Ball and Liam Plunkett have each accepted a formal written warning and fine for unprofessional conduct – unrelated to the investigations into Ben Stokes and Alex Hales – with undisclosed sums paid equally to the PCA Benevolent Fund and the Hornsby Professional Cricketers’ Fund.
“The internal investigation and process for this matter has now concluded and no further comment will be made,” the statement added.
But all five men feature in some form on the list of players handed contracts by the ECB.
Bairstow, Stokes, Moeen Ali, James Anderson, Stuart Broad, Alastair Cook, Joe Root and Chris Woakes have all been given Test contracts.
Hales meanwhile has been retained on his white-ball contract along with Stokes and a host of others: Moeen Ali, Jake Ball, Jonny Bairstow, Jos Buttler, Alex Hales, Eoin Morgan, Liam Plunkett, Joe Root, Adil Rashid, Jason Roy, Ben Stokes, David Willey, Chris Woakes, Mark Wood. There is also an incremental deal for Toby Roland-Jones.
“On these, I would like to congratulate all of those who have received England contracts for 2017/18, ahead of a busy year of international cricket,” Strauss added.
Once England arrive in Australia later this month, they will play three warm-up matches in which the third seamer’s slot and the middle order batting places will be up for grabs.
The first Test will then get underway in Brisbane on November 23.