Nine Aberdeen councillors could be kicked out of their party next month in a row over an “unauthorised deal” with the Conservatives.

Last May, Labour members incurred the wrath of then-Scottish Labour leader Kezia Dugdale when they teamed up with the Tories and independents to take control of Aberdeen City Council – despite the SNP having more councillors than any other party.

Ms Dugdale suspended the nine from the party and they have since branded themselves Aberdeen Labour.

Now, Scottish Labour’s executive committee (SEC) has put the membership of the councillors under review, months after saying it wanted to look at the administration’s budget before making a decision.

SEC chairwoman Cathy Peattie said: “We cannot endorse this deal and, following a year’s suspension, we are now left with no choice but to recommend the referral of the group to the body of the party that will consider their exclusion.

“On behalf of the Scottish Labour Party, I would like to put on record my thanks to the group for their work for the Labour Party over many years and express our regret that they chose to jeopardise their membership of the party by doing an unauthorised deal with another political group and independent councillors.”

The decision means Labour’s national executive committee (NEC) could throw them out of the party when it next meets on July 3.

While the group has remained in its council positions, expulsion from the party would mean its members would have to decide whether to stand against Labour-nominated candidates at the next election.

However, the NEC has previously indicated it favours the nine being welcomed back.

Aberdeen Labour group leader Councillor Jenny Laing said they were disappointed by the SEC decision but added: “The nine of us met on Saturday and we agreed to continue in administration. We deserve to stay in the party. Many of us have been in the party for many years. I myself have been in it for 35 years.”

However, SNP group leader Councillor Stephen Flynn said the “news should come as no surprise” to the suspended nine “given their decision to help the Tories push through cuts to vital council services”.

He added: “The SNP ran on a progressive manifesto that promised investment in infrastructure, community facilities and social care. The people of Aberdeen voted for change and the suspended Labour members did not listen.”

However, senior Labour figures have supported the councillors. Dame Anne Begg, Labour MP for Aberdeen South from 1997 to 2015, said: “The councillors have done everything asked of them as well as putting the interests of the people of Aberdeen and those who elected them first.”

And north-east Labour MSP Lewis Macdonald added: “There is no Scottish Labour policy position which prevents councillors or indeed MSPs from doing deals with any other party.”