* Stabenow says CFTC must restore confidence in oversight
* Senate Ag panel to hold hearing on financial markets
* Regulators still looking for missing $600 million
WASHINGTON, Nov 15 (Reuters) - Congress increased pressure on the U.S. futures regulator to sort through the mess left behind by the collapse of brokerage MF Global , and called for a hearing to examine whether proper market oversight is in place.
Senator Debbie Stabenow, the chairwoman of the Senate Agriculture Committee, said the bankruptcy of MF Global and the missing $600 million of customer funds raises questions about the dangers of excessive leverage and the adequacy of existing protections.
"That funds are missing highlights an extraordinary breach of trust - it is unacceptable that there are any doubts about the safety of customer assets," said Stabenow, a Michigan Democrat, in a letter sent on Tuesday to Gary Gensler, the head of the Commodity Futures Trading Commission.
MF Global filed for bankruptcy on Oct. 31 after investors and counterparties balked at revelations about the firm's bets on risky European sovereign debt.
A huge shortfall was discovered in the customer accounts of the company's brokerage, and the CFTC is among the authorities investigating whether MF Global may have improperly mixed that money with its own funds.
In the letter, Stabenow asked the CFTC a number of questions including what it is doing to monitor and protect segregated customer funds and what additional steps it plans to take to protect them.
A CFTC spokesman declined to comment on the letter.
She also said more needs to be known if bankruptcies such as MF Global's are preventable, and whether the current scope and frequency of audits are enough to understand a firm and whether it poses a risk to the market.
MF Global had a half dozen regulators policing various parts of the firm, but no one clear watchdog responsible for the whole company.
"The situation generally raises a number of questions about the varying regulatory responsibilities within these markets," Stabenow said.
The Agriculture Committee will be holding a hearing in the coming weeks on financial market oversight, which Stabenow said will look into MF Global and the authority and resources of the CFTC.