Officials in the US state of Minnesota say the Federal Bureau of Investigation (FBI) has refused to cooperate with their investigation into the death of Alex Pretti.

Federal agents shot dead the 37-year-old intensive care nurse during a protest against immigration enforcement in the city of Minneapolis on 24 January.

Minnesota's Bureau of Criminal Apprehension (BCA) has accused the FBI of failing to hand over any information and evidence from its investigation into the shooting.

BCA Supt Drew Evans called the FBI's actions "concerning and unprecedented". The FBI has not yet responded.

Minnesota's BCA said it would "welcome a joint investigation" with federal officials.

"The BCA is committed to thorough, independent and transparent investigations of these incidents, even if hampered by a lack of access to key information and evidence," it said in a statement.

Pretti's family has also pushed for a joint investigation, according to the BBC's US partner CBS News.

"Justice and accountability requires a thorough and impartial investigation to establish the facts. A truly joint state and federal investigation would be a welcome development," Pretti's family said in a statement.

A separate civil rights investigation into Pretti's death was announced by the Department of Justice in January.

The BCA said it is also investigating the shootings of Renee Good, who was killed by Immigration and Customs Enforcement (ICE) agents on 7 January, and a Venezuelan national who was injured after a car chase one week later.

"It remains unclear if there will be any co-operation or sharing of information related to those two shootings," the BCA said.

State and federal officials sparred over the course of Operation Metro Surge, an immigration crackdown launched by the Trump administration.

It prompted a wave of national protests opposing US President Donald Trump's migration policy and the tactics of ICE.

White House border tsar Tom Homan announced a "drawdown" of the Minnesota operation last Thursday.

More than 4,000 undocumented immigrants had been arrested, according to Homan, including men he said were convicted of rape and other sexual offences.

Minnesota's Democrat Governor Tim Walz said the operation left the state with "deep damage, generational trauma... and many unanswered questions".