Bundee Aki has apologised for his reaction at full-time in Connacht's narrow loss to Leicester Tigers, in which he angrily confronted referee Mathieu Raynal.

Connacht were beaten 29-28 in the Sportsground, substitute Hosea Saumaki scoring in the corner in the 79th minute to give the visiting Tigers a dramatic victory.

As the referee examined the replays of the decisive try on the big screen, the home support appeared convinced that Saumaki placed a foot in touch when holding off John Porch's last-ditch tackle.

Closer inspection of the replays from multiple angles indicated that Saumaki had successfully stayed in-field, though the crowd were dismayed when Raynal awarded the try, with only time left for Freddie Burns' immaterial failed conversion.

After the final whistle, a furious Aki led the charge in confronting Raynal to protest the decision, with the French official being heard to ask "If it's not on the line, you will apologise?"

After the game, Aki apologised to the referee on social media and vowed to "take the loss on the chin."

"Like to apologise about my action towards the referee and officials, kids who were watching. Absolutely not needed in this game," Aki wrote.

"Emotions were high and that is certainly not an excuse for my actions. Definitely will take the loss on the chin and will be looking at myself."

Connacht surrendered an 18-point lead in the second half, two tries from Tiernan O'Halloran and one each from Cian Prendergast and Kieran Marmion helping them into an authoritative 28-10 lead with just under 50 minutes on the clock.

However, Leicester rustled up the final 19 points of the game, scoring three tries, through Kini Murimurivalu (his second of the game), substitute hooker Charlie Clare and then Saumaki at the death.