The founder of Momentum, a key ally of Jeremy Corbyn, has succeeded in a bid to make the party effectively abolish its 40-year-old student wing, which is dominated by the more centrist side of the party.

Jon Lansman won the backing of Labour’s ruling national executive committee (NEC) for a motion that argued Labour Students was not officially affiliated and should be replaced.

The motion said Labour Students had not paid affiliation fees but this was disputed by Rania Ramli, its chair, who wrote to Jennie Formby, the party’s general secretary, setting out its case. Labour Students could now look at a legal challenge on the grounds it has been excluded on the basis of inaccurate information.

The move against Labour Students was condemned by a number of MPs as counterproductive at a time when the party should be focusing on preparing for an election rather than internal rows.

Several accused the NEC of targeting Labour Students because it has links with MPs on the more centrist side of the party and is not associated with Corbyn’s politics.

Wes Streeting, a Labour MP and former president of the National Union of Students as a Labour Students candidate, said: “The Labour party should be focusing all its energies on winning the next general election, not Jon Lansman’s factional vendettas against Labour Students. It is literally student politicking, when we’re in the fight our lives for the future of the country.”

Stella Creasy, another Labour MP, added: “Why at such a critical time in our country, and with an election on the horizon, does anyone who wants Labour to be an effective force for good think this is the time for such attempts to silence parts of our youth movement ,when we need them to be seen and heard campaigning?”

The motion put to the NEC said that the “organisation which currently describes itself as ‘Labour Students’ claims to be an organisation affiliated to the Labour party” but in fact did not meet all the terms required for affiliation. “The NEC therefore asks general secretary to urgently devise a plan to establish a Labour Students organisation which does meet its obligations,” it said.

The motion passed after a lengthy meeting of the NEC before next week’s party conference in Brighton.

A Labour party source said: “The NEC has asked staff to draw up proposals for a reformed student organisation that complies with the rules and represents the tens of thousands of students in our party.”

Labour Students reacted to the motion with dismay, saying it was based on “false and inaccurate claims which we have not had the opportunity to address”.

A Momentum source said: “It’s a victory for democracy that the rotten borough of Labour Students has finally been reformed. There are 30,000 students in the party and Labour students had just 507 students take part in their last election. It’s always been a bunker for a tiny clique who don’t care about building a broad student movement in Labour, and it’s right that the NEC have decided to overhaul it.”