FILE PHOTO: U.S. Secretary of State Mike Pompeo speaks at a joint news conference with President of El Salvador Nayib Bukele at the Presidential House in San Salvador, El Salvador, July 21, 2019. REUTERS/Jose Cabezas

WASHINGTON (Reuters) - U.S. Secretary of State Mike Pompeo on Monday dismissed Iran’s announcement it had captured 17 spies working for the U.S. Central Intelligence Agency and sentenced some to death.

Iran made the announcement in state media, saying the alleged spies had been arrested in the 12 months to March 2019. Such announcements are not unusual in Iran, but the timing has raised concerns that Tehran is hardening its position in its standoff with Western powers.

“The Iranian regime has a long history of lying ... I would take with a significant grain of salt any Iranian assertion about actions that they’ve taken,” Pompeo said in an interview with Fox News Channel.

Pompeo declined to comment about any specific cases, but added: “There’s a long list of Americans that we are working to get home from the Islamic Republic of Iran.”

In recent weeks, the United States has blamed Iran for a string of incidents in the Strait of Hormuz, an important shipping alley in the oil trade bordering one coast of Iran. Iran has denied the accusations.

On Friday, Iran seized a British-flagged oil tanker in the strait. Tehran had previously warned it would retaliate after the Britain captured an Iranian tanker off the coast of Gibraltar.

Asked about any possible U.S. role in the tensions, Pompeo said, “The responsibility ... falls to the United Kingdom to take care of their ships.”