The armed forces face a challenge in meeting recruitment targets
The US Army and Marine Corps recruited significantly more people with criminal records last year than in 2006, amid pressure to meet combat needs.
Statistics released by a congressional committee show 861 people were granted waivers to enlist, up from 457 in 2007.
The crimes included assault, sex crimes, manslaughter and burglary.
The Army says waivers are only granted after careful review and are in response to the challenges of recruiting in a changing society.
The number of people granted waivers are just a small fraction of the more than 180,000 people who entered active duty in the armed forces during the fiscal year that ended in September 2007.
But the perceived lowering of standards is causing concern in some quarters.
"The significant increase in the recruitment of persons with criminal records is a result of the strain put on the military by the Iraq war," said Democratic Representative Henry Waxman.
Mr Waxman chairs the House Oversight and Government Reform Committee that released the figures drawn up by the US Department of Defense.
These show that:
- The Army granted 511 felony waivers in 2007, up from 249 the year before
- Some 350 people with convictions joined the Marine Corps, up from 208 in 2006
- The Navy actually recruited fewer people with convictions, down from 48 to 42
- The Air Force did not recruit anyone with a felony conviction
Among the convictions, many were for stealing, including burglary and car thefts, and drug offences.
Waivers were also granted to three people convicted of manslaughter, nine guilty of sex crimes, and nine convicted of making terror threats, including bomb threats.
In addition, the Army and Marine Corps granted 27,671 "conduct waivers" covering what are regarded as serious misdemeanours , up from 25,098 in 2006.
Pentagon officials say that the need to recruit troops for continuing operations abroad, low unemployment at home, and declining interest in serving pose a challenge.
"We're digging deeper into the barrel than we were before," an official told the Washington Post.
The Army also argues that its ranks reflect the society they are drawn from.
Only three in 10 Americans of military age meet the army's medical, moral, aptitude, or administrative requirements, army officials point out.
"We're growing the army fast, and there are some waivers - we know that," said Army Lt Gen James Thurman, deputy chief of staff for operations.
"It hasn't alarmed us yet."