Neil Lennon said the Green Brigade were welcome back at the club after the controversial supporters' group made a surprise return to Celtic Park yesterday.

Around 200 fans entered the stadium five minutes before kick off in a game against St Johnstone and sang and banged drums behind a Green Brigade banner for the duration of Celtic's 3-0 victory, a result delivered by Anthony Stokes' hat trick. It was the group's first appearance inside the stadium since a Champions League match against AC Milan in November. At that game, a banner featuring IRA hunger striker Bobby Sands was raised in their section, resulting in a £42,000 fine for Celtic from UEFA.

In December the club suspended 128 supporters identified as being involved in discharging flares and vandalising seats at Motherwell's Fir Park, and also relocated around 250 season-ticket holders from Celtic Park's section 111 where the Green Brigade congregated.

Yesterday, the Green Brigade banner and chants returned as the fans gathered again at the same end of the ground, albeit in section 118 at the other side of the pitch.

Celtic had described the behaviour at Fir Park as "an embarrassment" and "absolutely indefensible", adding that there was an element of their fans which had no hesitation in bringing Celtic's name into disrepute. The club's tolerance of the Green Brigade appeared to be at an end and club sources said they would not be able to regroup elsewhere in the stadium.

However, when asked about the Green Brigade's return yesterday a Celtic spokeswoman said: "They were not banned. They bought individual match tickets."

Lennon has both praised and criticised elements of the Green Brigade's behaviour in the past but the Celtic manager was enthusiastic about their return yesterday. "Whoever they were - I don't know if they were the official Green Brigade or not - I can't thank them enough because they made a hell of a difference to the atmosphere today," he said.

"I would think that the players would have thrived on it. I got word this week that they might be in and I was delighted to hear that noise. You could tell by the rhythm of the game that they added to it. So long as everyone works within the rules of the club then we welcome that colour, energy, noise. It's been part of my time here for the last three-and-a-half years and we don't want to miss that because they brought a lot of good to the ground as well."

Meanwhile, Lennon said he was irritated by some newspaper headlines yesterday which suggested he was ready to leave Celtic in the summer - "I hope I will be here for the long haul, I haven't changed my mind on anything, I've got work to do here" - but purred about the performance which brought a 25th consecutive league match without defeat.

"It was the response I was looking for after last week [losing to Aberdeen in the Scottish Cup]," Lennon added. "There were great contributions from all the players. I thought Nir Biton was outstanding. I thought Leigh Griffiths on his home debut gave us real energy and spark and attacking impetus. 'Stokesy' got the goals that his performances over the past month deserved."

Tommy Wright, the St Johnstone manager, also praised Celtic for their performance "I thought Celtic were excellent. They were hurting from last week so it was no surprise that they played so well."