Iraqis employed by the U.S. government in Iraq should be granted "immigrant visas" to come to the United States at the end of their service, U.S. Ambassador to Iraq Ryan Crocker has written to the State Department in a two-page letter sent earlier this month.

The request comes as more and more Iraqis have quit their U.S.-backed jobs and are seeking refuge with 2.2 million others in neighboring Syria, Jordan and other countries. According to the U.N. High Commissioner for Refugees, each month 60,000 Iraqis flee their homes.

"Our [Iraqi staff members] work under extremely difficult conditions, and are targets for violence including murder and kidnapping," Crocker wrote Undersecretary of State Henrietta H. Fore, according to the July 9 letter first quoted by The Washington Post. "Unless they know that there is some hope of an [immigrant visa] in the future, many will continue to seek asylum, leaving our Mission lacking in one of our most valuable assets."

In the last three years, at least nine Iraqi U.S. Embassy employees have been killed there, including a married couple last month. Iraqi employees other than interpreters and translators generally cannot get U.S. immigrant visas. Estimates on he numbers of Iraqi employees with the U.S. Embassy vary from fewer than 200 to a few thousand.

While the State Department has not commented on the letter, it has said previously that it would sped up visas for Iraqis. However, despite agreeing to process 7,000 visas for pro-U.S. Iraqis, the department has only admitted 133 Iraqi refugees since October.

Congress continues to pressure the State Department with bipartisan legislation to expand U.S. refugee and immigrant visas.

FOX News' Julie Kirtz contributed to this report.