WASHINGTON - Arrests and deportations of immigrants living illegally in the United States plummeted in 2021 compared with 2020, while more of those arrested were convicted of serious crimes in keeping with a shifting strategy under U.S. President Joe Biden, an agency said in a report released on Friday.

Overall, U.S. Immigration and Customs Enforcement (ICE) made about 74,000 arrests of immigration offenders in the 2021 fiscal year, which ended on Sept. 30. That is a 28 percent decrease compared with the previous year and the lowest total in over a decade, according to the agency's data reviewed by Reuters.

ICE deportations of immigrants also plunged in 2021 - to 59,000 compared with 186,000 in 2020. The 2021 total was the lowest since 1995, according to government data.

Of those arrested in fiscal year 2021, approximately 12,000 were people convicted of what is known as an "aggravated felony," which includes violent crimes but can also include non-violent misdemeanors.

The total of those with serious criminal histories was nearly double a year earlier, reflecting a move by Biden's Democratic White House to prioritize the arrest of more serious offenders and de-emphasize enforcement against non-criminals in contrast to former President Donald Trump, a Republican.

"As the annual report's data reflects, ICE's officers and special agents focused on cases that delivered the greatest law enforcement impact in communities across the country while upholding our values as a nation," acting ICE Director Tae Johnson said in a related news release.

In a setback for Biden, the U.S. Senate on Tuesday night unexpectedly delayed a vote on Biden's pick to run the agency, Harris County, Texas, Sheriff Ed Gonzalez.

The delay came after Republican Senator James Lankford raised concerns over an allegation of domestic abuse that Gonzalez denies.

(Reporting by Ted Hesson in Washington; Additional reporting by Kristina Cooke; Editing by Mica Rosenberg and Howard Goller)