NEW YORK (Reuters) - A leading proxy advisory service on Thursday urged Citigroup Inc (C.N: Quote, Profile, Research) shareholders to oppose the re-election of four outside directors, including three members of the largest U.S. bank's compensation committee.

ISS Governance Services recommended the defeat of Alcoa Inc (AA.N: Quote, Profile, Research) Chief Executive Alain Belda, retired Chevron Corp (CVX.N: Quote, Profile, Research) Chairman and Chief Executive Kenneth Derr, Time Warner Inc (TWX.N: Quote, Profile, Research) Chairman Richard Parsons, and Xerox Corp (XRX.N: Quote, Profile, Research) Chief Executive Anne Mulcahy.

Citigroup's annual meeting is scheduled for April 22 in New York.

ISS, a unit of RiskMetrics Group Inc (RMG.N: Quote, Profile, Research), said Belda, Derr and Parsons do not deserve re-election because Citigroup has "poor pay practices." The three men sit on Citigroup's personnel and compensation committee, which Parsons chairs.

It cited $9.5 million of guaranteed incentives granted last year to Chief Financial Officer Gary Crittenden, and various awards and perquisites to former Chairman and Chief Executive Charles Prince, who resigned under pressure in November.

Meanwhile, ISS said Mulcahy may be overextended from running Xerox, and sitting on the boards of Xerox, Citigroup, Target Corp (TGT.N: Quote, Profile, Research) and The Washington Post Co (WPO.N: Quote, Profile, Research).

"While CEOs benefit from their exposure to other company boards, the time demands of their full-time jobs limit the number of outside commitments they can manage without compromising their effectiveness," ISS said.

On Wednesday, another proxy advisory service, Egan-Jones Proxy Services, urged Citigroup shareholders to withhold votes to re-elect another director, former AT&T Corp (T.N: Quote, Profile, Research) Chief Executive C. Michael Armstrong. It cited his role overseeing the bank's audit and risk management committee.

Citigroup lost $9.83 billion in the fourth quarter, and has suffered more than $20 billion of write-downs and credit losses since the global credit crisis erupted last summer. Analysts expect another multi-billion-dollar loss in the first quarter.