The England and Wales Cricket Board has defended its disciplinary procedure after it emerged the promising English seamer Craig Overton was found to have told Sussex’s Pakistan-born batsman Ashar Zaidi to “go back to your own fucking country” during a county match last season.

Overton, who came close to selection for England’s winter Test tour to South Africa, was reported to have made the remark by both the umpire Alex Wharf, at the bowler’s end, and the non-striking batsman Michael Yardy in the 57th over of Somerset’s four-day Division One match away to Sussex at Hove which began on 14 September.

The Guardian understands Wharf included this in his report, with Yardy giving a written statement in support. Zaidi, who was playing for Sussex on his British passport before being released by the club at the end of the season, told the match officials he had not heard anything beyond the “usual” comments that did not upset him.

Sent the evidence from Yardy and Wharf by the ECB, the Cricket Discipline Commission went on to give Overton a level one breach for using abusive language, the lowest of the four in the ECB directives. A level three breach is the first that covers “language that vilifies another person on the basis of race or national origin”.

The verdict stands in contrast with the case of Yorkshire’s captain, Andrew Gale, in 2014, in which the ECB appealed for a longer ban after a similar exchange between Gale and Lancashire’s South African batsman Ashwell Prince.

The announcement of the charge against Overton, which incurred an automatic two-match ban because of two previous minor offences on his record, came only two days after Overton had been named on England’s performance programme – the overseas winter training camp for players considered next in line for international selection.

Despite this squad being picked after the ECB had learned of the incident at Hove – but before his punishment was announced – the board has denied any suggestions that an emerging player on the radar of the selectors was spared the more serious level three breach.

An ECB spokesperson told the Guardian: “Following the incident, the on-field umpires sought advice from the ECB’s cricket department, who referred the matter directly to the chairman of the Cricket Discipline Commission, Mr Gerard Elias, QC.

“After reviewing the umpires’ report, the chairman of the CDC gave clear guidance that this should be reported as a level one offence and that no further action would be taken by the CDC. The automatic penalty for a level one offence was subsequently applied and this took Craig Overton to nine points, the threshold for an automatic suspension.

“The Cricket Discipline Commission is an independent body which operates at arm’s length from the ECB.

“Craig Overton’s selection for the EPP squad would have played no part whatsoever in the CDC’s ruling in this matter. The ECB refutes any suggestion of interference or bias in the proper disciplinary process.”

Overton, who denied Wharf and Yardy’s claim in his submission, sat out Somerset’s final match of the season and will miss his side’s 2016 opener at Durham.

With this ban akin to chalking up points on a driving licence, a previously clear record for Overton would have seen this incident met with only a reprimand.

The issue has raised the questions over consistency in punishments handed out by the CDC, as well as the ECB’s response. In 2014, Gale was banned for two matches after telling Prince to “fuck off back to your own country, you Kolpak fucker”, only for the ECB to complain to the CDC about Gale’s conduct and see this suspension extended by a further two games as a result.

Gale was also barred from lifting the County Championship trophy at Trent Bridge when Yorkshire sealed the title that September, a decision that continues to rankle at the club, despite their successful defence last summer in which he finally got his hands on the silverware.

There was no official response to the Overton case from Yorkshire but, privately, senior figures are concerned by what they perceive as double standards within the game.

Somerset have declined to comment on the Hove incident publicly, although a club official told the Guardian that, in their view, it differed to that of Gale at Old Trafford as Overton had already turned away from the batsman, who did not hear it, while their player also denied the comment in his evidence.

In Overton’s case, according to documents seen by the Guardian, it was only Wharf and Yardy who heard the alleged comment. Yardy, batting with Zaidi at the time, challenged Overton’s use of language immediately, telling him: “You can’t say that”, with Wharf then consulting with his senior colleague Ian Gould at the end of the over.

Because of the nature of the comments, and without wanting to disrupt the game, they agreed to discuss the matter after the close of play before contacting the ECB head of cricket operations, Alan Fordham, at Lord’s, via telephone, to make him aware of the situation and request advice.

The following morning Wharf, Gould and the ECB cricket liaison officer, Graham Cowdrey, met Overton and Somerset’s head coach, Matthew Maynard, in the indoor school at Hove to outline the offence in person.

While Overton did not speak, Maynard suggested the comment could have been aimed at his own Somerset team-mate Tom Cooper, an Australian cricketer who plays for the club on a Dutch passport, following an earlier mis-field. Both were given a player conduct report in order to fill out the relevant player’s comments section.

After this meeting the umpires met Yardy, who provided a written statement in support of what Wharf reported he had heard on the field. Zaidi was then asked whether he had heard the words “go back to your own fucking country” but replied that he had not heard anything beyond “the usual” comments.

Given the nature of the incident, Somerset advised Cowdrey that Overton would not take the field for the remainder of the match, with his 14th over, in which the incident took place, his final contribution; a 12th man replaced him, with the all-rounder’s absence later explained as a “hand injury”.

Ashar Zaidi strikes a boundary for Sussex during the County Championship match against Somerset. Photograph: ProSports/Rex Shutterstock

The player conduct report, completed by the umpires Wharf and Gould, and Yardy’s statement were then sent to Fordham at the ECB offices. From there, the day after the match concluded, the CDC announced, via a press release, that Overton had incurred a level one breach of the directives – “using language that is obscene, offensive or insulting and/or making an obscene gesture”.

With Overton having chalked up two previous offences in 2015 – the first for physical contact on the field away to Worcestershire in May, the second for abusive language in the match prior to the Hove incident, at home to Hampshire – he was automatically suspended for Somerset’s next two games. Uncapped Overton took 43 championship wickets last season as Somerset avoided relegation and was nominated for the PCA Young Player of the Year. He was recently revealed to have been “close” to being named for the upcoming Test tour to South Africa by the national selector, James Whitaker.

Speaking about the matter ahead of the tour, England captain Alastair Cook said: “Everyone knows the full responsibility you have when you pull on that shirt. You are under extra scrutiny, whether you’re with Somerset or England. Of course you want [players] to give everything for the cause but there’s a line you should not go past.”

Overton was one of seven emerging fast bowlers to feature in a 12-day England training camp in Potchefstroom, South Africa, in November before an elbow injury resulted in him being withdrawn from the current Lions squad playing in the ongoing Twenty20 series against Pakistan A in the United Arab Emirates.

Both he and his twin brother, the fast bowler Jamie Overton, were added to the England one-day squad that beat New Zealand 3-2 in the early part of the summer but did not feature in the series.

From the moment the brothers began playing for Somerset, English cricket has eagerly anticipated the possibility that they could become the first twins to represent England in international cricket.