KINSHASA (Reuters) - Two U.S. citizens on trial in the Democratic Republic of Congo over their role in an attempted coup in May, told a court on Friday that they were threatened by the coup leader to either join or be killed.

Armed men briefly occupied an office of the presidency in the capital Kinshasa on May 19 before their leader, U.S.-based Congolese politician Christian Malanga, was killed by security forces.

Speaking for the first time since the trial began, Malanga's son Marcel Malanga, 22, and Benjamin Zalman-Polun told the court that the coup leader had threatened them.

"Dad had threatened to kill us if we did not follow his orders," Malanga told a military court, denying they had any involvement in plotting the coup attempt.

He said he had come to Congo to see his father, whom he had not seen since 2021, at his invitation, adding he had not visited the country before.

"I am American, I do not speak French or Lingala," he told the military court in the capital Kinshasa.

Malanga and Zalman-Polun are among over 50 people that include U.S., British, Canadian, Belgian and Congolese citizens standing trial following the failed coup.

They face various charges including illegal arms possession, criminal conspiracy, and terrorism, attempts to destabilise state institutions and undermine the integrity of the state, some of which risk the death penalty or lengthy prison sentences.

Zalman-Polun told the court that he was a long-time business associate of Malanga, but had nothing to do in planning the coup attempt.

"I met Malanga in 2013, we always had relationships based on mining activities in Swaziland and Mozambique, he had never been so violent," Zalman-Polun told the court.

The trial was adjourned until Monday July 8.

(Reporting by Ange Kasongo; Writing by Bate Felix; Editing by Alex Richardson)

By Ange Kasongo