Image caption Alleged misconduct reportedly occurred while Hillary Clinton was Secretary of State

The US state department failed to fully investigate allegations against its officials involving prostitution, a drug ring and assault, media report.

A leaked internal document obtained by CBS News said staff protecting ex-Secretary of State Hillary Clinton regularly solicited sex workers.

The reports also allege a drug ring may have provided narcotics to state department contractors in Iraq.

But it is suggested officials may have tried to cover up the misconduct.

According to CBS, a draft copy of a state department inspector general's report alleges eight specific examples of improper behaviour by US officials.

'Criminal behavior'

Some allegations were suppressed, according to CBS, such as an investigation into an unnamed ambassador who was said to be visiting prostitutes in a public park.

The document cites allegations that the envoy "routinely ditched his protective security detail in order to solicit sexual favors from both prostitutes and minor children".

It went on to say that the ambassador's security team and other colleagues "were well aware of the behavior", according to the reports.

CBS reports that attempts to look into the allegations were stopped in their tracks.

According to the broadcaster, the copy of the draft report said: "Hindering such cases calls into question the integrity of the investigative process, can result in counterintelligence vulnerabilities and can allow criminal behavior to continue."

CNN also reports that the inspector general found an attempt to investigate claims that a drug ring near the US embassy in Baghdad was supplying illegal substances to state department security contractors was stopped.

It was also alleged that a state department security official in Beirut "engaged in sexual assaults" against foreign nationals hired as embassy guards. The same person was accused of similar attacks during previous foreign postings, according to CNN.

Meanwhile, members of Mrs Clinton's security detail solicited prostitutes on official trips, a problem the leaked report is said to have described as "endemic".

Aurelia Fedenisn, who was an investigator with the state department's inspector general, told CBS: "We also uncovered several allegations of criminal wrongdoing in cases, some of which never became cases."

The inspector general's office has reportedly asked external law enforcement experts to look at the way the state department handles complaints of serious misconduct by its senior staff.

Findings are expected later in the summer.

State department spokeswoman Jen Psaki said: "We take allegations of misconduct seriously and we investigate thoroughly.

"All cases mentioned in the CBS report were thoroughly investigated and under investigation, and the department continues to take action."