Kabul- A government watchdog is raising fresh concerns that U.S. funds meant to help pay Afghan police salaries may instead be going to "ghost workers," according to a letter he sent to military commanders in Afghanistan.

John Sopko, the special inspector general for Afghanistan reconstruction, said his staff has initiated an audit on the reliability of personnel data for Afghan National Security Forces, including how such data are used to calculate payrolls for Afghan National Police officers.

"I am writing to express my concern that the U.S. may be unwittingly helping to pay the salaries of non-existent members of the Afghan National Police," Sopko wrote in his February 19 letter to two U.S. generals and one Canadian general in the NATO mission.

"The possibility of 'ghost workers' on the (Afghan National Police) payroll came up several times in the course of my most recent visit to Afghanistan and in recent discussions with European Union (EU) representatives."

Worries about insufficient accountability have long dogged the "Law and Order Trust Fund for Afghanistan" (LOFTA), established by the United Nations Development Programme in 2002. LOFTA's website says the fund supports payment of salaries of more than 140,000 Afghan police officers.

Sopko noted that the European Union had withheld 100 million euros in planned contributions from the trust fund "due to concerns about how that money is being used, including the possibility of payments to ghost workers and other instances of financial mismanagement."

The United States has provided 38 percent of the $3.17 billion that the international community has contributed to the trust fund since 2002, Sopko wrote. In a March 12 reply to Sopko, U.S. Army Major General Kevin Wendel, the head of the Combined Security Transition Command for Afghanistan, said his command was "aggressively pursuing this issue."

"But (our command) has not found evidence that anyone knowingly paid for non-existent workers," Wendel wrote. Wendel acknowledged discrepancies between personnel and payroll records, which he said prompted a need to "reconcile approximately 54,000 erroneous personnel I.D. numbers" in the fund's database.

But Colonel Jane Crichton, a spokeswoman for U.S. forces in Afghanistan, said in response to a query by Reuters that did not mean those were ghost workers. She said more than 99 percent of the 54,000 ID card numbers identified had already been reconciled - "indicating no 'ghost employees.'"

For its part, the United Nations Development Program, asked by Reuters about concerns over ghost workers, said there had been improvements in the "efficiency and accountability" of the payroll system for the Afghan National Police.

"The (Afghan) government is committed to upgrading its police payroll system to remove all opportunities for corruption," a UNDP spokeswoman said.

Wendel, in his letter, said he had also requested the Defense Department's Inspector General to carry out a comprehensive review of how payroll funds were accounted for within the Afghan financial system.

"Our work is far from complete," he wrote, citing a need for continued self-assessments and improvement. The DOD's Inspector General was expected to release a draft report in May and the final report in July, Crichton said.