Zambian opposition leader Brian Mundubile is now being questioned by police, state broadcaster ZNBC reports.
Mundubile, who leads the National Reconciliation Party for Unity (NRPUP), had been in hiding since disputing the results of the 13 August presidential election. Official results gave incumbent President Hakainde Hichilema 60% of the vote, with Mundubile on 38%.
Tensions escalated a day after the vote when security forces raided a property linked to Mundubile in Lusaka. During the raid, former cabinet minister Mutotwe Kafwaya was killed and several other opposition figures were arrested. Authorities accused the opposition of planning an armed uprising, a claim the NRPUP denied.
After the raid, Mundubile said he moved to a secure location under the protection of an international human rights body due to threats against him. ZNBC said he and his running mate Makebi Zulu had been under UN protection in Lusaka.
Both men are now being interviewed by law enforcement officers in the presence of their lawyers. Police issued the summons over what they describe as alleged activities that could threaten national security.
The opposition has not been able to challenge the election in court. On Monday, the final day to file a petition, the courts were sealed off by authorities.
President Hichilema is scheduled to be sworn in for a second term on 1 September.
