The move to freeze pounds 2m of funds held by MeesPierson will come as unwelcome news to the court-appointed liquidator of Griffin, as well as the Securities and Futures Authority (SFA), which are keen to avoid a messy legal battle.
The traders have also set up a fighting fund to pursue their claims, and have retained City solicitors Williamson & Horrocks.
The traders claim that funds used by MeesPierson to clear John Ho Park's pounds 6m losses included their own funds which should have been held in separate "designated" accounts. The Dutch bank cleared transactions for Mr Park on the Eurex exchange.
MeesPierson was unavailable for comment.