Islamic extremists demanded millions of dollars in ransom before brutally executing captured American photojournalist James Foley, according to a report.

A Foley family representative and a former fellow hostage with the freelance journalist told The New York Times that captors with the Islamic State in Iraq and Syria (ISIS) sought $100 million for Foley's release.

The U.S., unlike some European nations that have paid millions in exchange for their citizens, would not pay the terrorists.

The family of Foley, who freelanced for the Boston-based GlobalPost news service and went missing in Syria in November 2012, reportedly received an email last week from the Islamic militants. But it did not include any demands, GlobalPost Chief Executive Philip S. Balboni said Wednesday, according to The Boston Globe.

Some fellow hostages with Foley were released after ransoms were paid, Balboni added.

GlobalPost spent "millions" in an attempt to get Foley, Balboni said, according to the Globe.

“There were monetary challenges that were not going to be easy to overcome," he said.

Balboni told The Wall Street Journal the original demand for Foley was $132.5 million (100 million euros) but did not discuss the company's reply.

ISIS is holding three other Americans as well as some British citizens, according to the Times. The U.S. made an unsuccessful attempt at rescuing the hostages this past summer, administration officials said Wednesday.

Earlier in the day on Wednesday, President Obama said the U.S. would be "relentless" and "vigorous" in protecting Americans abroad.

Obama said the world was "appalled" by the beheading of Foley by ISIS, which was posted in a video online Tuesday, and called for "a common effort to extract this cancer so that it does not spread."