The Saracens academy player who triggered the Ben Stokes captaincy crisis by throwing a punch at his England teammate Gus Atkinson has escaped without being disciplined.

The Guardian understands that Totoa Auvaa, a 21-year-old Samoan back-row, will not face formal disciplinary action from Saracens or the Rugby Football Union despite throwing a punch at Atkinson.

Auvaa’s punch missed Atkinson and struck an England and Wales Cricket Board (ECB) security guard, who was sufficiently injured to require stitches, but opted not to report the matter to the police.

Saracens pledged to review the incident and address it appropriately after learning of the flare-up in a Chelsea nightclub a fortnight ago, a process that has now concluded.

A source with knowledge of the Saracens investigation claims that, while Auvaa had been given a stern talking-to and warned about his conduct, the former Samoa Under-20 captain has not been formally sanctioned.

Saracens confirmed to the Guardian that their review has concluded but declined to go into further details.

The RFU has not launched an investigation despite having overall control of discipline in the sport in England, with sources saying they regard it as an employment matter between the player and his club.

The ECB is understood to be bemused that no action will be taken against Auvaa, given that Stokes and Atkinson were both dropped from last week’s second Test match against New Zealand before their own investigation concluded that they were blameless victims of unprovoked violent attacks.

In a statement released earlier this week confirming that Stokes and Atkinson would return to the side for the third Test against New Zealand, which began on Thursday, the ECB referred to “unprovoked attacks” and multiple “incidents” in the Rex Rooms in Chelsea in the early hours of Monday 8 June.

In addition to missing the second Test, Stokes and Atkinson were both given formal written warnings by the ECB for breaching the terms of their central contracts.

“No blame should be attached to the players for violent conduct at the nightclub,” the ECB statement said. “Stokes was not involved in the altercation and did not witness either incident. The evidence the ECB has seen demonstrates that Atkinson was the victim of unprovoked attacks and did not retaliate on either occasion.”

Saracens players were enjoying their end-of-season party at the White Horse pub in Chelsea when they ran into England players celebrating their first Test win over New Zealand at Lord’s on Sunday 7 June.

Some of the players already knew each other and were reportedly getting on well, but there was an altercation at the nearby Rex Rooms later in the evening after most of the England players had returned to their hotel.

Saracens have not commented since releasing a statement to Sky Sports News two weeks ago, which said: “The club is currently establishing the full facts and is in contact with the relevant authorities and individuals involved. Once this process is complete, the matter will be reviewed and addressed appropriately.”

Auvaa has not played a senior game for Saracens and spent last season on loan at the Champ side Ampthill, but is highly rated at the club and expected to be given a senior contract.