US President Donald Trump has signed legislation banning the use of software by Moscow-based Kaspersky Lab within US government networks.

The ban is part of a broader defense policy spending bill, the National Defense Authorization Act.

It caps a months-long effort to purge the antivirus firm from federal agencies amid concerns it was vulnerable to Kremlin influence.

“The case against Kaspersky is well-documented and deeply concerning. This law is long overdue," said Democratic Senator Jeanne Shaheen, who led calls in Congress to scrub the software from government computers. 

"Going forward, I will continue to push for additional measures that strengthen our nation’s cybersecurity and protect our democracy from harmful foreign interference.” 

In September, the Department of Homeland Security issued a ban on Kaspersky products. The agency also expressed its concerns regarding “the ties between certain Kaspersky officials and Russian intelligence and other government agencies, and requirements under Russian law that allow Russian intelligence agencies to request or compel assistance from Kaspersky and to intercept communications transiting Russian networks.”

Kaspersky Lab has repeatedly denied that it has ties to any government and said it would not help a government with cyber espionage. In an attempt to address suspicions, the company said in October it would submit the source code of its software and future updates for inspection by independent parties.

US officials have said that step, while welcomed, would not be sufficient.

In a statement on Tuesday, Kaspersky Lab said it continued to have “serious concerns” about the law “due to its geographic-specific approach to cybersecurity.”

It added that the company was assessing its options and would continue to “protect its customers from cyber threats (while) collaborating globally with the IT security community to fight cybercrime.”

On Tuesday, Christopher Krebs, a senior cybersecurity official at the Department of Homeland Security, told reporters that nearly all government agencies had fully removed Kaspersky products from their networks in compliance with the September order.

Kaspersky’ official response to the ban did not appear to contain any information that would change the administration’s assessment of Kaspersky Lab, Krebs said.