GAZA, June 27 (Reuters) - Hamas forces seized $16,000 on Sunday from a Gaza bank that had frozen the funds as part of an anti-money laundering campaign launched by the West Bank-based Palestinian Authority.

A senior official at the Palestine Islamic Bank (PIB) said Hamas police took the cash from tellers at gunpoint. No one was hurt in the incident. Hamas officials had no immediate comment.

The bank said the money was in an account of an Islamic charity frozen by the Interior Ministry and Palestine Monetary Authority (PMA), which acts as a central bank for President Mahmoud Abbas' Palestinian Authority, Hamas's rival.

The account was frozen after Hamas, which won a Palestinian parliamentary election in 2006 and took control of the Gaza Strip in 2007, brought in its own people to manage the charity.

It was the second time Hamas seized money from a private Palestinian bank this year. In March, its forces took $400,000 from a bank in defiance of the PMA, raising concerns among bankers over the safety of operating in Gaza.

Mahmoud Al-Ram'a, general manager of PIB, said owners of the frozen account had sued the bank in Gaza and the Hamas men who seized the money said they were executing a court order. Gaza courts are overseen by the enclave's Hamas-run Justice Ministry.

We are working in two different legal environments which makes our job harder. This is the main problem of the banking sector in Palestine, Ram'a told Reuters.

The PIB reports to the PMA.

He said he expected a recurrence of Sunday's incident because the West Bank-based Interior Ministry had frozen several similar accounts in the Gaza Strip since the Hamas takeover three years ago.

Around a dozen banks, Palestinian- and Arab-owned, still function in the Gaza Strip, though their headquarters are in the West Bank.

Israel, along with the United States, considers Hamas a terrorist organisation. Israeli banks severed ties with Gaza banks in 2007 as part of a tightening of an embargo on the Islamist-ruled territory. (Reporting by Mohammed Assadi)