The controversy comes a day after Edinson Cavani thought he had opened the scoring for Manchester United at Tottenham, only for the goal to be disallowed for a foul in the build-up as Scott McTominay brushed off Son Heung-min.

Like the Red Devils, West Brom were not affected by the decision as Matheus Pereira's penalty and goals from Matt Phillips and Callum Robinson earned a crucial victory.

Allardyce said: "I'm afraid so (it's becoming a laughing stock). The reflection on VAR can be done at the end of the season and all parties should have an influential input into how VAR goes forward.

"That needs to be from the PFA, LMA, Premier League and the FA. There are too many of us not being given an opportunity to express how to make it better."

Sam Johnstone capped a fine night for the Baggies by saving a stoppage-time James Ward-Prowse spot-kick to preserve his clean sheet.

Albion, who last week posted a shock 5-2 win at Chelsea, remain second bottom but are eight points from Premier League safety with seven games remaining after recording successive wins for the first time this season.

Allardyce's side now do not play again until travelling to Leicester next Thursday and the boss insisted their pleas to face Aston Villa on Saturday were blocked, leaving them to hope their relegation rivals drop points beforehand.

"We've got it down to eight (points) but games are running out. We don't have a game this weekend," said Allardyce. "Me and Dean Smith (Aston Villa boss) wanted to play the Villa game this weekend but for some bizarre, unearthly, reason it's not been allowed.

"We have to sit and hope. Instead of us putting pressure on the teams above us we have to wait until the following Thursday when we play Leicester and that's wrong."

Albion were the best side throughout and, after Diagne's disallowed strike, opened the scoring after 32 minutes.

Diagne and Ainsley Maitland-Niles combined to tee up Pereira and he was chopped down by Fraser Forster before drilling the penalty down the middle.

Three minutes later, it was 2-0 when Phillips converted Diagne's excellent cross from the left at the far post.

Southampton improved after the break but Albion always looked comfortable and added a key third goal after 69 minutes when Okay Yokuslu slipped in Robinson and he beat Forster at the near post.

There was no way back for the visitors and Ward-Prowse had a stoppage-time penalty saved by Johnstone after Conor Townsend fouled Moussa Djenepo.

The Saints now face Leicester in Sunday's FA Cup semi-final and boss Ralph Hasenhuttl knows they must drastically improve.

He said: "It was a non-performance. We missed everything which is normally part of our game. When you make it that easy for the opponents it's not a surprise when you are 2-0 down.

"In the second half, we changed a few things in our behaviour but it's too late sometimes. It's difficult, we are all responsible for performances like this.

"It's not really a serious question, we know if we play like this today we have no chance (on Sunday).

"I think we have shown we can do it much better. When you are like this in a game it's tough against a team fighting for everything.

"The best test for the weekend is a strong performance here to get some self confidence. We have to be very critical with this game because it's far away from what we can normally offer."