(CNN) -- An adviser to Saudi Arabia's government denied Thursday there is any kidnapping threat for Westerners in Riyadh, adding that he has "no idea" what prompted U.S. officials to issue such a warning.
On Wednesday, the U.S. Embassy in Saudi Arabia said it had received information that a terrorist group may be planning abductions in the Saudi capital. The embassy passed along the notice in an emergency message for U.S. citizens.
But the adviser to the Saudi government -- responding to questions from CNN by e-mail Thursday -- said "we were not told about the intelligence or warning ahead of time and have no idea what it is based on."
"It may be credible, it may not, we have no idea at this point," he added.
The adviser criticized the content of the warning, including its mention of a "terrorist group" and "demonstrations," which he said were not happening.
"The way the warning was written is completely unacceptable," he said. "There is (not) a terrorist group running around Riyadh threatening to kidnap expatriates."
Deputy U.S. State Department spokesman Mark Toner said Wednesday that he could not comment on specific intelligence, but said there was no reason for U.S. citizens to leave Saudi Arabia.
"We deemed the information to be credible, or would not have issued the emergency message," he said.
The Saudi adviser said there was "no precedent" for the warning, vowing a reaction in a "very stern manner" if it is based on "circumstantial evidence."
"The hype that this warning is causing is absolutely unwarranted, and we will not tolerate it," he said. "The achievements of the Saudi counter-terrorism program will not be put into question or belittled by the Americans or anyone else for that matter!"
CNN's Jill Dougherty contributed to this report.