Travelers agent logins and passwords to costco.com, a popular travel agency that is widely used by US travelers, will be restricted after an FBI investigation, the company said in a blog post on Thursday.

US law enforcement agencies have been looking into whether the FBI was targeting US-based travel agents, including some with the Travel Agency, and whether agents with the agency were compromised, a US government official told the Associated Press news agency.

US officials said earlier this week that the FBI had discovered a cyberattack on the agency, which they called a “targeted, sophisticated” cyberattack.

A spokesperson for the FBI said on Wednesday that the agency was “actively investigating the hack” and that it “will not tolerate threats to the national security”.

US President Donald Trump has long spoken out against travel agents and their agents and employees.

On Wednesday, he tweeted: “Travel agents and agents with Travel Agency are targeted, sophisticated, and are being compromised by foreign intelligence services.

No excuses!”

He added: “My Administration will take steps to ensure the safety of our country and our citizens.”

US travel agents have long been targets of attacks and hacks.

Last year, hackers stole more than 10 million personal details from some 40,000 agents and workers.

US travel agency Travel Agents International reported the hack on Wednesday and said it was investigating.

The FBI has said the agency “did not breach our network, but it was compromised by cyber actors who gained access to our systems”.

The FBI said that it had “zero tolerance” for cyber attacks against agents, their staff and their properties, the Associated News news agency reported.

The hack comes as the agency’s travel agents face pressure from many travelers and business travellers, who are worried about how their details could be accessed by hackers and others.

Last week, the agency said it would no longer accept American passports for travel to the US.

US President Barack Obama has also called for travel agents to get more information about travel restrictions and said that US agents “need to have more of a sense of their safety” as well as be more transparent.