Cairo (Reuters) - Sudan's military has dissolved the boards of all state companies and national agricultural projects, state TV said on Friday, in what appeared to be the junta's latest move to tighten control after seizing power in a coup on Oct. 25.

       Under growing international and domestic pressure, the military rulers were challenged by a leading civilian group to release three political figures it said had been arrested after meeting an envoy for the United Nations.

       Last week's takeover halted power-sharing between the military and civilians which was agreed after the overthrow of long-time autocratic leader Omar al-Bashir 2 1/2 years ago and meant to lead to elections by the end of 2023.

       State TV gave no further details on the dissolution of state company boards.

       Mediation efforts involving the United Nations have sought the release of figures including Prime Minister Abdalla Hamdok, who is under house arrest, and a return to power-sharing.

       But the Forces of Freedom and Change (FFC) coalition said three more - two Sudanese Congress Party members and a senior member of a task force dismantling the Bashir government's assets - had been arrested on Thursday.

       The U.N. mission in Sudan condemned the reported arrests near its offices in the capital Khartoum and called for the immediate release of those detained.

       (Reporting by Lilian Wagdy and Khalid Abdelaziz; Writing by Aidan Lewis; Editing by Toby Chopra and Andrew Cawthorne)