By Rajesh Kumar Singh

CHICAGO (Reuters) - Another U.S. senator has joined a chorus against Pennsylvania-based NonLethal Technologies Inc for selling riot gear to Hong Kong that is being used against pro-democracy protesters.

The privately held company, which makes and exports a wide range of riot and crowd control equipment for military and law enforcement agencies, has been in the spotlight ever since it was discovered that Hong Kong police are employing its tear gas canisters to disperse anti-government demonstrations.

In one photo that has been widely shared on social media, NonLethal's name is stamped on the casing of a spent tear gas canister.

The use of U.S.-made gear to quell protests has prompted several lawmakers to call for halting and even banning tear gas exports to the city. In July, Senator Ted Cruz, a Republican, proposed in a tweet that the United States consider banning exports of tear gas to Hong Kong if the attacks on the protesters were not stopped.

Similarly, in August, U.S. Representatives Chris Smith, a Republican, and James McGovern, a Democrat, wrote to Secretary of State Mike Pompeo and Secretary of Commerce Wilber Ross, asking them to suspend future sales of crowd and riot control equipment to Hong Kong police.

They followed up their letter with a bipartisan bill in the House of Representatives last month, which seeks to prohibit commercial exports of certain nonlethal crowd control items and defense articles and services to the city. If passed, the ban would take effect within 30 days.

U.S. Senator Rick Scott, a Florida Republican, on Thursday became the latest to raise concerns about the exports.

In a letter to NonLethal's president shared on Twitter, Scott said the sales were equivalent to supporting efforts of the Chinese president to "harm ordinary citizens and peaceful protesters." He urged the manufacturer of tear gas to "put human rights above profits."

The protests have plunged the city, an Asian financial hub, into its worst crisis since it returned to Chinese rule in 1997, posing the biggest popular challenge to Chinese President Xi Jinping since he came to power in 2012.

What began as opposition to a now-withdrawn extradition bill has evolved into a pro-democracy movement fanned by fears that China is stifling Hong Kong's freedoms, guaranteed under a "one country, two systems" formula introduced in 1997.

China denies the accusations and says foreign countries, including Britain and the United States, are fomenting unrest.

In his Oct. 10 letter, Scott said during a recent trip to the city he saw firsthand how the company's products were used in a "dangerous and malicious manner to intentionally harm protesters."

He requested to meet with the company's president, Scott Oberdick, to discuss his concerns.

Oberdick, however, told Reuters on Friday that he had not seen Scott's letter. When asked about the criticism his company has been facing for selling tear gas to Hong Kong police, Oberdick hung up the phone.

NonLethal does not share its financial details with public. However, in 2017, it was listed as one of the top 10 companies in the world producing riot-control systems, according to London-based market research firm Visiongain.

According to its website, the company provides "a full range of less lethal grenades and less lethal ammunition to allow the most effective level of force to be used for various situations." However, for overseas sales, most of its products require an export license from the United States Department of Commerce.

An online petition, urging the White House to suspend any export application of crowd control equipment to Hong Kong, has garnered more than 110,000 signatures.

Amnesty International has also called on countries including the United States to halt all transfers of less lethal "crowd control" equipment - including water cannon vehicles, tear gas, pepper spray, rubber bullets, projectile launchers and parts and components - to Hong Kong.

(Reporting by Rajesh Kumar Singh in Chicago; Editing by Matthew Lewis)