A Palestinian bank has frozen the accounts of Hamas' security force after mistakenly paying the wages of 3,000 of the group's members, officials say.
Hamas routed Fatah forces in the Gaza Strip in mid-June
The Gaza branch of the Palestine Islamic Bank says it acted at the request of the Palestinian Authority.
A spokesman for Hamas Islamist group described the move as illegal.
Tensions between Hamas and its rivals from Palestinian leader Mahmoud Abbas' Fatah faction have been high since Hamas seized control of Gaza in June.
The Palestine Islamic Bank on Monday froze the accounts of at least 3,400 members of Hamas' Executive Force.
Hamas immediately denounced the move.
Hamas spokesman Ehab al-Ghsain said that "legal procedures could be taken against the bank in the coming hours," Reuters news agency reported.
The group also held the bank's manager for questioning.
Some 3,000 members Hamas' main force were paid the salaries earlier this month before the mistake was noticed.
The payments were halted and most were reversed, Fatah officials said.
But hundreds of Hamas men reportedly were able to cash their salary cheques.