Two major newspapers are now counting the number of people killed by police in the United States, as the debate over the use of deadly force by officers, especially against minorities, rages on.

More than two people were killed by police each day, and most were black or Hispanic, according to lists compiled by The Washington Post and The Guardian.

The counts are based on police reports and witness statements, as well as local news, research groups and open-source reporting projects.

The Guardian is counting all people killed by police, while the Post is only including those shot to death.

The US federal government relies on partial data because the country's 17,000 or so state and local police agencies are not required to report such killings.

The lack of official data has fed some of the growing public frustration over a series of police killings since the fatal shooting of unarmed black teenager Michael Brown in Ferguson, Missouri in August touched off weeks of sometimes violent protests.

On Monday, The Guardian unveiled a database it dubbed "The Counted," which encourages readers and witnesses to contribute.

An interactive map identifies the number of people killed by age, region or ethnic background.

"Within minutes, we had submissions," Jon Swaine, a lead reporter on the project, told AFP.

He expressed hope that readers -- who can send photo or video documentation anonymously -- will become the main source of the database. Each submission is verified by journalists.

The Post, which reported its initial findings at the weekend, found that relative to the overall population, blacks were killed at three times the rate of other minorities or whites in the police killings so far this year that it analyzed.

The report noted that most of the people killed were armed with potentially lethal objects -- mainly guns, but also knives and other items. Sixteen percent were carrying a toy or were unarmed.

Among the unarmed victims, two thirds were black or Hispanic.

"The police departments are not required to refer to the federal authorities" about killings at the hand of law enforcement, explained the Post's Wesley Lowery.

"They can do it voluntarily."

He called for Congress to pass a law mandating federal statistics and funding data collection.

- Five months, 400 dead -

The Post found that so far this year, at least 385 people have been shot and killed by police across the United States -- a rate of more than two a day.

The Guardian counted 464 dead over the same period.

Data on shooting fatalities is "easier to collect and it's more accurate," Lowery explained.

But Swaine explained that if only police shootings are counting, then that excludes victims like Baltimore resident Freddie Gray, whose death from a spinal injury suffered in police custody sparked riots.

A quarter of those killed suffered from mental illness, according to the Post.

In one case, in Florida, police killed a schizophrenic man who was waving a broomstick.

His mother had called law enforcement because she was unable to get him to come back inside despite cold temperatures.