FBI Director Christopher Wray warned lawmakers on Thursday that there is a growing fear among law enforcement officials of a "coordinated attack" inside the US after an ISIS assault on a concert hall in Moscow last month killed 145 people and wounded hundreds more.

"Our most immediate concern has been that individuals or small groups will draw twisted inspiration from the events in the Middle East to carry out attacks here at home," Wray told a House Appropriations subcommittee in prepared remarks.

"But now, increasingly concerning is the potential for a coordinated attack here in the homeland, akin to the ISIS-K attack we saw at the Russia concert hall

"Looking back over my career in law enforcement, I'd be hard pressed to think of a time where so many threats to our public safety and national security were so elevated all at once," Wray said, according to his prepared remarks.

The March 23 attack in Moscow by the Islamic State group's Afghanistan affiliate has raised concerns that the group could carry out similar attacks in the United States and Europe.

Wray has issued similar warnings about threats to US security in the past.

He was to appear Thursday before the appropriations committee for a budget hearing titled the "Fiscal Year 2025 Request for the Federal Bureau of Investigation".

The FBI had requested a budget of $11.3 billion.

A fiscal 2024 package passed by the House earlier this week and being considered by the Senate would fund the FBI at $10.7 billion, or $654 million less than the fiscal 2023 enacted level, according to a House Republican summary.

Wray was to say in his prepared remarks that budget cuts "to us are cuts to our partners — state and local law enforcement agencies and officers who are on the ground, putting themselves in the line of fire — often quite literally".

"This is by no means a time to let up or dial back. This is a time when we need your support the most — we need all the tools, all the people, and all the resources required to tackle these threats and to keep Americans safe."

On March 22, four gunmen affiliated with ISIS-K, a terrorist group that largely operates out of Afghanistan and Pakistan, stormed Moscow's Crocus City Hall ahead of a sold-out concert, killing at least 145 people and wounding 551 more.

Wray's renewed warning about the threat environment will come amid his testimony on the bureau's fiscal year 2025 budget request.

Wray made his comments one day after telling an American Bar Association luncheon in Washington that foreign adversaries and terrorist groups are sharpening their aim at the United States -- targeting cyber operations, security and "mafia-like" tactics in an "increasingly concerning" way.