Speaking from a hotel after arriving in South Sudan's capital, Juba, Arman said on Monday: "I was deported against my will".
"I was deported against my will".
He will also discuss the situation with the Ethiopian Prime Minister, Abiy Ahmed, who has been trying to mediate between the military council and the opposition in Sudan, before later travelling to Mozambique and South Africa.
Day two saw a sweeping nationwide internet blackout which rocked the country for several hours, after internet lines from the main provider Sudatel stopped working.
In response, the opposition called a general strike that began on Sunday, the first day of the workweek in Sudan, to keep up pressure on the military, which had cancelled a power transfer agreement that called elections within nine months following the dismissal in April of the civilian regime of Omar al-Bashir.
The plan appears to build on a proposal made by the Ethiopian premier during his mediation visit to Khartoum last week, the news agency said, without divulging the identity of the opposition leader.
Yasir Arman addresses the media in Juba, South Sudan, on Monday.
But protesters remained outside army headquarters in Khartoum to demand that the military council hand over to civilian rule, before they were dispersed in a crackdown that left dozens dead.
The military council announced that security forces on the streets would be boosted after four people were killed in clashes on Sunday - two in Khartoum and two in Omdurman, just across the Nile river.
The report comes on the second day of the opposition's general strike, with the majority of shops and businesses closed in the capital, Khartoum.
Protesters had set up several roadblocks across many areas of the capital that the ruling generals have vowed to remove in order to bring "life to normal".
"I have to work to support my family or else we will have no money".
Tensions have soared in Sudan since security forces violently broke up a protest camp in central Khartoum a week ago, killing dozens of protesters.
Also on Monday, Deputy U.N. spokeswoman Eri Kaneko told reporters in NY that the military council had decreed to the African Union-U.N. peacekeeping mission in Darfur to hand over its premises to Sudan's Rapid Support Forces (RSF) as part of the mission's withdrawal in 2020.
Witnesses said the RSF, which grew out of Arab militias that fought in Darfur, led the assault on the protest sit-in in Khartoum last week.
"The military council has chose to reinforce the presence of armed forces, RSF and other regular forces to help normal life return", a general said late on Sunday.
The overall death toll since June 3 has reached 118, according to a doctors committee linked to the protesters who are pressing the military to hand over power to a civilian administration. The health ministry says 61 people died nationwide on June 3, including 49 by "live ammunition" in Khartoum.