Mitch Landrieu is New Orleans's first white mayor in three decades
New Orleans's new mayor has asked the US government to investigate the city's scandal-plagued police department.
Mitch Landrieu, who took office on Monday, said the force had been described as "one of the worst" in the country.
In a letter to the US attorney general, he noted officers had been implicated in violent crimes including rape.
New Orleans is struggling to rebuild nearly five years after the devastation that followed Hurricane Katrina.
Police shooting deaths
A spokesman for the US justice department civil rights division, which typically handles investigations into law enforcement agencies, said the department would consider Mr Landrieu's request and determine if any action was appropriate.
New Orleans police officers are currently the subject of at least eight federal civil rights investigations.
In one case, three officers have pleaded guilty to covering up the police shooting death of two refugees fleeing the floods that inundated New Orleans after Hurricane Katrina.
And earlier this week, a New Orleans officer was suspended from duty following his arrest on a domestic violence charge.
"Although most sworn [New Orleans Police Department] officers honour their commitment to protect and serve each day, an independent investigation is needed," Mr Landrieu wrote on Wednesday to US Attorney General Eric Holder in Washington.
"It is clear that nothing short of a complete transformation is necessary and essential to ensure safety for the citizens of New Orleans."
However, in remarks to the local Times-Picayune newspaper, Capt Henry Dean, president of the local police union, questioned the need for federal oversight, noting that Mr Landrieu had already pledged to co-operate in a local inquiry.
'Ineptitude, mismanagement, corruption'
Mr Landrieu on Thursday named a new police superintendent, in what he said would be a first step towards reform.
Ronal Serpas, currently chief of the Nashville police department in Tennessee, is a New Orleans native and was formerly a high-ranking official in the New Orleans force.
The mayor's request for federal help came a day after a coalition of community groups sent a letter to the justice department pleading for intervention.
"Our local police, elected officials and local federal agencies have sat silently for years, complicit in the brutality of [New Orleans Police Department] ineptitude, mismanagement, corruption and abuse of power," the Louisiana Justice Institute wrote.
Federal intervention in a local law enforcement agency is relatively rare. Since 1 January 2009, the justice department has opened only four investigations.
Should the justice department act in New Orleans, it could bring criminal prosecutions against individual officers or could force the department to alter policies, procedures and practices.
The US has nearly 17,000 police and sheriff's departments, ranging from one-person rural agencies to the New York Police Department, which boasts more than 35,500 sworn officers. New Orleans has about 1,400 police officers.
The city was already struggling with a high crime rate before Hurricane Katrina devastated its infrastructure in summer 2005, emptying large swaths of the city and tearing communities apart.
In 2008, New Orleans's murder rate was more than 10 times the national rate, with 179 murders and non-negligent homicides in the city of 281,000, according to FBI statistics.
Mr Landrieu is the first white mayor of New Orleans to be appointed in more than three decades.
He was elected with strong support from both white and black voters, replacing Ray Nagin, the mayor who for many came to symbolise the city's halting recovery from Katrina.
Mr Landrieu hails from a Democratic Louisiana political dynasty - his father Moon Landrieu was mayor of New Orleans in the 1970s, and his sister, Mary Landrieu, is a US senator for the state.
New Orleans residents hope their new mayor's connections in Washington will help win more federal aid for the city.