The general secretary of the Labour Party and former union official, Jennie Formby, has been accused of refusing to meet staff to discuss pay rises.
In an email seen by HuffPost UK sent to party staff who belong to the GMB union, representatives said a meeting with management had “not been forthcoming”.
Party workers who are members of the Unite union are also impacted.
Formby, who took over the running of the party machine in April last year, previously worked as political director and south-east England regional secretary for Unite.
The row comes as Jeremy Corbyn ramped up his calls for a general election which would put extra pressure on party workers.
“The JTUC (joint trade union committee) have been trying to meet with management to discuss the pay request, which was submitted in October 2018, alongside other issues,” the email from GMB sent on Friday said.
“Our reps have been working alongside Unite colleagues to arrange a meeting but it has not been forthcoming.
“The latest communication received by our workplace representatives says that a meeting will be arranged in early February.”
The email added: “Once we have any further information regarding the pay offer we will update all branch members.
“If no meeting date is set between the JTUC and management by mid-February, we will hold a branch meeting to discuss how to proceed.”
A Labour Party spokesperson said: “We don’t comment on staffing matters, but it’s simply not true to say the general secretary has refused to meet with staff unions and representatives over pay.
“The Labour Party values the relationship with its staff unions and treats pay negotiations confidentially and with respect.”
The dispute over pay within the party comes as Corbyn repeated his demand for a general election to break the Brexit deadlock.
“What we should do is have a general election and give people their right to choose the government for the future – to negotiate sensibly with the European Union,” he said today.
James Cleverly, the Tory deputy chairman, told HuffPost UK last week his party was “always ready” for an election.
But he said even if there was another snap poll it would not resolve the impasse in parliament.