The decision to allow Darren Bent's bizarre winning goal against Liverpool has been described as "amazing" by a former Premier League referee.

The Sunderland striker's low drive struck a large red beach ball lying on the edge of the Liverpool six-yard box and deflected past goalkeeper Pepe Reina for the only goal of the match.

Referee Mike Jones allowed the goal to stand after consulting with his assistant, but his decision has been criticised by Jeff Winter and Dermot Gallacher, the former top-flight referees.

"It is basic law in football," Winter said. "The goal should just not have stood. The laws state that if there's an outside interference the game has to be stopped. Talk about an outside influence - the ball went in off the beach ball and completely deceived the Liverpool goalkeeper.

"I am absolutely amazed that for a referee at that level of football, that between him, his assistant, the fourth official, they didn't see what had happened and give the correct decision."

Dermot Gallacher agreed: "It was such a glaring error," he said. "Everybody knows that when something encroaches on to the pitch the game stops."

According to Fifa's Laws of the Game, the goal should have been disallowed. In a section titled 'Interpretation of the Laws of the Game and guidelines for referees', under the title 'Powers and duties', it is stated that "the referee stops, suspends or abandons the match because of outside interference of any kind".

TV footage showed that the beach ball was punched on to the Stadium of Light pitch by a young Liverpool supporter minutes before Bent's controversial goal. Pictures showed the beach ball lying to the side of the Liverpool goal and then tucked into the back of the Liverpool net, but it had blown into the six-yard area before Sunderland went on their crucial attack.

The post-match reactions of Rafael Benitez, the Liverpool manager, and Steve Bruce, his Sunderland counterpart, suggested that they were unclear as to what decision should have been given.

"It's a very technical question, but it could be because it could have been a goal anyway," Benitez said. "In this case, I think it should be a goal."

"I thought it was a deflection off a player," Bruce said. "I have to say that if anybody knew that rule - that it is supposed to be a drop-ball - then you are a saddo."

In January 2008, Sheffield United scored a similarly fortunate goal against Manchester City in the FA Cup fourth round. Michael Ball, the City left back, attempted to clear a cross, but missed the ball entirely when it bounced off a stray balloon lying in the six-yard area. Luton Shelton pounced to open the scoring and United went on to win 2-1.