Football Federation Australia has admitted the Wellington Phoenix were denied a penalty.



The New Zealand team should have been playing 10 men before All Whites defender Ben Sigmund was incorrectly sent off by Australia's World Cup-bound referee Ben Williams during an incident-packed A-League stalemate with Melbourne Heart on Sunday, it said.



A damning appraisal of Williams' officiating during a dramatic 2-2 cliffhanger at AAMI Park in Melbourne is still scant consolation to the Phoenix.



The team had been desperate to secure three competition points to close in on the top six with only four regular season games remaining.



FFA director of referees Ben Wilson said Williams had made two key blunders that affected the eighth-placed Phoenix's prospects of victory.



He also conceded the Heart's second equaliser was debatable, without condemning veteran Harry Kewell for diving to win a penalty.



Phoenix coach Ernie Merrick had been critical of the match officials and FFA match review panel for failing to act when Reece Caira and Kenny Cunningham were elbowed by Adelaide and Perth Glory opponents respectively in Wellington's two previous games.



He at least received public acknowledgement this time that the officials had erred after an inquiry by Fairfax Media.



However, it was hollow victory as the Phoenix face a mounting injury toll and question marks considering the form and fitness of marquee import Carlos Hernandez as they confront a tense run in, starting with Saturday's clash with the Jets in Newcastle.



Wilson told Merrick by email last week that Perth goalkeeper Jack Duncan should have been sent off and his replacement challenged to stop the resulting penalty when Cunningham was flattened at Westpac Stadium on March 9.



But no action was taken by the match review panel because referee Jarrad Gillett saw the incident and did not deem it worthy of serious punishment - a scenario that irked the usually amiable Scot.



Merrick was also upset there was no FFA investigation after rookie defender Caira suffered a season-ending fractured cheekbone when he was elbowed by Adelaide's Tarik Elrich during the Phoenix's 5-1 loss on February 27.



Gillett was also in charge of that match and he was not appointed for last weekend's round - though the FFA denied his omission amounted to punishment.



"Not necessarily," a FFA spokesman told Fairfax Media.



"We've only got five games a weekend and we have quite a large number of referees (13) on the panel. I wouldn't draw any conclusions based on that."



Williams, the Asian Football Confederation's referee of the year in 2013, will not be involved this weekend either - he will be attending a pre-World Cup Fifa workshop in Europe.



Wilson, in a statement released to Fairfax Media, said Williams "missed a deliberate handball incident involving Melbourne Heart defender Patrick Kisnorbo, which should have resulted in a penalty kick to Wellington and a red card.



"In the same match I believe the second yellow card issued to Ben Sigmund [for a tackle on Kewell] for breaking up a promising attack was an incorrect call, albeit not completely clear cut."



Sigmund received his first caution for impeding a goal-bound David Williams on the half hour and exited three minutes later after jostling Kewell for the ball - a sanction that exerted more pressure on a back four already comprising inexperienced defenders Michael Boxall and first-time starter Shaun Timmins.



Wilson said the Heart's penalty - converted by Williams - understandably sparked debate, as did Brisbane striker Besart Berish's red card against Sydney FC for a lunge at Seb Ryall.



"Opinions will always be divided on some decisions and in these instances it is important to uphold the notion that the match officials are responsible for making decisions on a football field and they get the majority of decisions right," he said.