Washington (AFP) - The US government put 271 Syrian chemists and other officials on its financial blacklist Monday, punishing them for their role in the deadly chemical weapons attack on a rebel-held town in early April.

In one of its largest-ever sanctions announcements, the US Treasury Department took aim at the Syrian Scientific Studies and Research Center (SSRC), which it said was responsible for developing the alleged sarin gas weapon used in the April 4 attack.

The attack left 87 dead, including many children, in the town of Khan Sheikhun, provoking outrage in the West, which accused Syrian President Bashar al-Assad of being responsible.

The sanctions include a freeze on all assets in the United States belonging to 271 individuals on the blacklist, and block any American person or business from dealing with them.

According to the Nuclear Threat Initiative, a Washington-based think-tank, the SSRC is Syria's leading scientific reasearch center, with close links to the country's military.

The center itself was already the subject of two sanctions declarations, in 2005 and 2007, due to its alleged role in developing weapons of mass destruction.

The Treasury said in a statement Monday that the SSRC is specifically behind the Syrian government's efforts to develop chemical weapons and the means to deliver them.

The 271 either have specific scientific expertise for the program or have been involved in it since 2012, it said.

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"These sweeping sanctions target the scientific support center for Syrian dictator Bashar al-Assad’s horrific chemical weapons attack on innocent civilian men, women, and children," Treasury Secretary Steven Mnuchin said.

"The United States is sending a strong message with this action that we will hold the entire Assad regime accountable for these blatant human rights violations in order to deter the spread of these types of barbaric chemical weapons."

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The Treasury's action followed the US military's firing 59 Tomahawk cruise missiles at a Syrian airfield on April 7 to punish the government and set a warning against any further chemical weapons attacks.

"These sanctions are intended to hold the Assad regime and those who support it -– directly or indirectly –- accountable for the regime's blatant violations of the Chemical Weapons Convention and UN Security Council Resolution 2118," Mnuchin said.

The attack on Khan Sheikhun was also debated in the UN Security Council. But Russia, a close ally of Assad, vetoed a resolution on April 12 demanding the Syrian government cooperate with an investigation of the attack.

Assad has denied the attack, branding it a "fabrication" by the West.

The US Treasury already had imposed sanctions against 18 Syrian officials in January. The sanctions effectively aim to shut those targeted out of global financial networks, making it difficult for them to do business or even travel.

Mnuchin said the administration "will relentlessly pursue and shut down the financial networks of all individuals involved with the production of chemical weapons used to commit these atrocities."