Hammonds' chief of international projects and finance William Abraham has resigned in a last-ditch attempt to get the firm to refocus its global strategy.
The firm is holding emergency talks with Abraham next week to address his concerns.
"The firm wasn't addressing Abraham's concerns that his international practice had been sidelined following its strategy review resulting in a more UK-focused approach," said one former partner.
As an emergency measure following its financial crisis Hammonds instituted a lock-in agreement, which only allows equity partners to resign on two specific dates during the year.
The most recent date was 30 September, when Abraham and Leeds-based property partner Simon Meek handed in their resignations.
"With equity partners only able to resign at two specific times in the year, William thought he should do it now as he couldn't stay at the firm under the current conditions until the next round in April," said a source.
A Hammonds spokesperson said the firm has a total of seven partners dealing specifically with project transactions and is looking to strengthen the team.
The spokesperson added: "We're committed to domestic and international project work, and if he does leave, we'll be replacing William in his role as head of international projects."