The U.S. on Sunday offered up to $5 million for information about the attackers who unleashed terror in India's largest city 10 years ago in a horrifying siege that killed 166 people, including six Americans.

Secretary of State Mike Pompeo announced the reward in a statement, calling for justice for the families of the victims in Mumbai.

10 YEARS ON, MUMBAI MOVES ON FROM ATTACKS BUT SCARS REMAIN

"It is an affront to the families of the victims that, after ten years, those who planned the Mumbai attack have still not been convicted for their involvement," Pompeo said. "We call upon all countries, particularly Pakistan, to uphold their UN Security Council obligations to implement sanctions against the terrorists responsible for this atrocity, including Lashkar-e-Tayyiba and its affiliates."

The reward, which was offered by the State Department's Rewards for Justice Program, is extended to those with "information leading to the arrest or conviction of any individual who was involved in planning or facilitating the 2008 Mumbai attack."

India's financial capital with a population of over 18 million, Mumbai turned into a war zone on Nov. 26, 2008, as a group of Pakistani gunmen who launched coordinated attacks on the city. They targeted two luxury hotels, a Jewish center, a tourist restaurant and a crowded train station. Three days of carnage killed 166 people, including foreign tourists, and wounded hundreds more.

FLASHBACK: SEE PHOTOS FROM THE 2008 MUMBAI TERRORIST ATTACKS

The focal point of the assault was the iconic Taj Mahal Palace hotel. Thirty-one people died inside the hotel, including staff trying to guide the guests to safety. Images of smoke leaping out of the city landmark have come to define the 60-hour siege.

India blamed the attack on the Pakistani militant group Lashkar-e-Taiba, throwing relations between the nuclear-armed neighbors into a tailspin. Indian officials accused Pakistan's intelligence agency of working with the militant group to mastermind the attack — an allegation Islamabad denied.

Pompeo, in his statement, said the U.S. stood with the friends and family of those who "were lost in this act of barbarism, including six American citizens. The barbarity of 26/11 shocked the entire world."

Fox News' Kelly Phares and The Associated Press contributed to this report.