The US Food and Drug Administration is looking into products made by two Indian spice makers for allegedly containing a cancer-causing pesticide.
Earlier this month, Hong Kong suspended sales of three spice mixes made by MDH and another by Everest over alleged high levels of ethylene oxide.
MDH and Everest products are among the most popular in India and worldwide.
Everest has previously said its products are safe for consumption, while MDH has not commented.
"The FDA is aware of the reports and is gathering additional information about the situation," an FDA spokesperson told Reuters news agency.
Singapore has also recalled the Everest mix for fish curries, saying the alleged high levels of ethylene oxide posed a cancer risk.
India's Spices Board - the government's regulator for spice exports - said earlier this week that it was seeking information on both companies' exports in Hong Kong and Singapore, and was working with the, to find the "root cause" of the quality issues as inspections started at their plants.
Both companies' websites were offline on Saturday.
Ethylene oxide is used for several purposes in industry, including as a fumigating agent for spices. The US's Environmental Protection Agency says the chemical is carcinogenic to humans.
"Evidence in humans indicates that exposure to ethylene oxide increases the risk of lymphoid cancer and, for females, breast cancer," the EPA wrote in 2018.
The BBC has contacted MDH and Everest for comment.
Back in 2019, a few batches of MDH products were recalled in the US due to fears of salmonella contamination.