An international aid organization says South Sudan's military has released six of its workers who had been arrested in January and accused of smuggling arms.

Doctors Without Borders told The Associated Press Monday that the aid workers were arrested Jan. 4 in the Yei area on suspicion of transferring weapons to the opposition, charges denied by the Switzerland-based organization.

However, South Sudan's Information Minister Michael Makuei insisted on Monday that the charges are valid. He added that the released workers left Yei without permission.

Two of the international workers were released on January 27th and the four others were released on March 31st.

International aid organizations are facing increasingly hostile conditions in South Sudan even as they help the country respond to famine and other humanitarian crises.