Prime Minister Andy Burnham has said Russell Brand has rightly been held to account for his “horrific” crimes and sought to explain Labour’s previous association with the comedian.

Some within the Labour Party attempted to court Brand’s support more than a decade ago, before police began investigating him – and in 2014 Burnham posted a supportive message on social media when the comedian was facing media criticism.

Asked about the 2014 tweet on Friday, Burnham said: “It’s not always the case that people know everything about people in public life.”

Brand was found guilty of one count of rape and three counts of sexual assault on Thursday.

In 2014, Brand was writing regular opinion pieces for newspapers and appearing on political discussion programmes, including the BBC’s Question Time.

His anti-establishment and left-wing views had also gained him a following on social media.

Ed Miliband, then the Labour leader, was interviewed by Brand in the run-up to the 2015 general election.

Brand, who had previously dismissed the idea of voting, backed Labour following the interview, saying Miliband had convinced him that “this bloke will listen to us”.

Miliband, who is now foreign secretary, has since said he regrets being interviewed by Brand. The BBC has approached Miliband for further comment.

In 2014, Burnham, then the shadow health secretary, posted on Twitter in support of Brand following allegations about the comedian’s housing arrangements.

It is not clear what Burnham had been referring to in his 2014 tweet, but the previous day, The Sun claimed Brand had paid rent at a property owned by a landlord in a tax haven, while at the same time campaigning against tax avoidance.

Brand threatened to sue the newspaper and said he would give the money to victims of the Hillsborough disaster, a group Burnham has long campaigned for.

At the time, Burnam said it was “depressing to see media mission to discredit someone who stops playing their game” and urged Brand to “keep going”.

Asked about that social media post on Friday, Burnham told the BBC “all I can say is I had no idea of the full extent of what he was doing or what he went on to do”.

The PM added: “His [Brand’s] crimes are horrific, he’s rightly been held to account, justice for the victims and that is the right course that’s been taken here.

“It’s not always the case that people know everything about people in public life, but what is important is that where there is wrongdoing it is exposed.”

The prime minister added: “Credit to the victims, huge credit, the courage that it’s taken, but also the journalists who’ve exposed this.”

Brand was found not guilty of two other counts of rape, and one count of attempted indecent assault.

During a four-week trial, Brand faced allegations from six women spanning the decade between 1999 and 2009.

The 51-year-old was refused bail and will spend the weekend in custody before he is due to return to court on Monday for sentencing.