Aston Villa's troubled end to the season has taken another damaging turn after the Midlands club suspended Ian Culverhouse, their assistant manager, and Gary Karsa, the head of football operations, pending an internal investigation.

Although the development raises fresh questions about Paul Lambert's future, the Villa manager's relationship with both men had broken beyond repair and the Scot was supportive of the club's decision to take action against them.

Furthermore Randy Lerner, Villa's owner, and Paul Faulkner, the club's chief executive, continue to stand shoulder to shoulder with Lambert despite growing supporter unrest, another relegation battle and what, in effect, is an admission from the manager that the backroom staff he appointed in 2012 were part of the problem this season.

Exact details have yet to emerge of the official reason behind the suspensions but it is known that Culverhouse and Karsa, who had worked with Lambert for the past eight years, including spells at Norwich City, Wycombe Wanderers and Colchester, had upset staff and players with their approach, creating what has been described as "a poisonous atmosphere".

Culverhouse, who spent 10 years at Carrow Road as a player, took the majority of the training at Villa and is believed to have been a highly influential figure at the club. His methods, however, had started to come under greater scrutiny, with resentment and concern building among players. There was an incident on the training ground a couple of weeks ago which left Fabian Delph and Gabriel Agbonlahor upset.

It has emerged that problems with Culverhouse and Karsa were longstanding. Lambert's once extremely close alliance with the pair unravelled and disintegrated to the point that there was a total loss of trust, culminating in tension that surfaced again at Crystal Palace on Saturday, when another altercation – believed to have taken place in the dressing room – preceded a fourth successive Premier League defeat, leaving Villa only four points clear of the relegation zone before Saturday's visit of Southampton.

The situation with Culverhouse and Karsa had become so serious that Villa felt compelled to act.

The club confirmed in a statement on Tuesday that Culverhouse and Karsa, who also worked together at Barnet and Leyton Orient prior to linking up with Lambert, had been suspended. An inquiry, involving Villa's legal advisers and overseen by the club's human resources department, is expected to be concluded before the end of the season.

In the meantime Gordon Cowans, a development coach at the club, and Shay Given, the out-of-favour former Republic of Ireland goalkeeper, have replaced Culverhouse and Karsa with immediate effect, with Lambert overseeing those appointments. "I'm delighted to have Gordon and Shay to assist me in preparing the team for Saturday, which is what the whole group is focused on," the Villa manager said.

Given's promotion to the coaching staff comes as something of a surprise – he has been frozen out under Lambert and not made an appearance for the club since the 2-1 FA Cup defeat against Millwall 15 months ago – but he is highly respected among the players and has remained an influential voice in the squad, despite being relegated to the role of third-choice goalkeeper.

The 37-year-old has been taking his coaching badges and, with one eye on the future, may see this as the first step in a future career.

With Cowans, a European Cup winner in 1982 and a hugely popular figure within the club, also on board, Villa are confident the changes will create a much more positive mood among the players, as well as the supporters, during the final five, potentially crucial, matches of the season.