Bangladeshis are at great risk of being targeted by human traffickers, said USAID Deputy Administrator Bonnie Glick.
The risk is even higher at the Teknaf-Ukhia border because of the large number of Rohingyas there, she said.
Bangladesh received a Tier 2 ranking in the international human trafficking index.
The government must work hard to prevent human trafficking, and if the situation does not improve, US aid might be stopped, she warned.
She made the comments after visiting the Victim Support Centre run by the YPSA (Young Power in Social Action- a local specialised social development organisation) in Cox's Bazar on Thursday.
Bonnie Glick also said the Rohingya crisis is a global issue now and that Myanmar is responsible for the crisis.
Bangladesh has earned the respect of the international community by giving shelter to more than 11 lakh Rohingyas, she said
Meanwhile, Alice G Wells, US assistant secretary at the Bureau of South and Central Asia, also visited the Rohingya refugee camp in the Shaplapur area of Teknaf.
Both the teams met Refugee, Relief and Repatriation Commissioner Mahbub Alam Talukder at his office in Cox's Bazar after the visit to the victim support centre and the camp.
After the meeting, Alice G Wells told the press that Myanmar has failed to create a conducive environment for Rohingyas to return to their place of origin in Rakhine State; therefore, it is unsafe for Rohingyas to return to Myanmar.
The US government wants a safe, voluntary and sustainable repatriation of the Rohingyas, and the US government and the international community have been playing an important role in addressing the Rohingya issue, she said.
Regarding the Bangladesh government's Rohingya relocation plan to Bhashan char, USAID Deputy Administrator Bonnie Glick said independent experts are yet to determine if the island is a suitable location for the Rohingyas.
She observed that the relocation of the Rohingyas to Bhashan char will be possible if the local administration and aid agencies can come to an agreement about the relocation plan.
US Ambassador in Dhaka Earl R Miller and UNHCR Representative Steven Corliss were present at the meeting.