The firm said the detention order was based on an inaccurate allegation that the shipments contained products that were produced using forced labor.
PureCircle said it was committed to human rights and has been certified by independent auditors to ensure compliance with the Sedex Members Ethical Trade Audit (SMETA) which requires that "there is no forced, bonded or involuntary prison labour used".
Stevia is a plant extract used in Coca-Cola Coke Life and other drinks.
The group also confirmed that its product, including shipments being withheld by US customs is not sourced from Inner Mongolia Hengzheng Group Baoanzhao Agricultural and Trade LLC.
It said it had submitted relevant documentation of this, including independent, third party verification to the US authorities and said it was working with them to correct the inaccurate information in the detention order communication and to expedite the release of our shipments.
PureCircle added today: "Depending on the duration of the detention order there could be some impact on sales and profit in the current financial year."
House broker Liberum said the announcement had understandably hit the share price but believes it will prove to be a buying opportunity.
"PureCircle has a fully audited supply chain and has submitted the relevant documentation to correct the innacurate information and to allow shipments to be released."
"We expect this issue to be resolved but given PureCircle has a June 30th financial year, the delay of shipments into the US may impact FY16 results," it added.
The broker estimates that $10 to 15mln of revenues and $5 to 7mln of net profit could be shifted from full year 2016 into full year 2017 but said it was waiting to hear on the speed of resolution before making changes to its estimates.
Shares in London shed 12.4% to 318p.