Key organisers of last week's anti-government protests in Malawi have gone into hiding amidst fears that they will be arrested.
"I will smoke you out," President Bingu wa Mutharika warned six organisers on Friday.
One of them, Rafiq Hajat, told the BBC he had gone into hiding and was leading a "solitary existence".
Nineteen people were killed during two days of protests last week against the high cost of living in Malawi.
Mr Mutharika deployed the army in the capital, Lilongwe, the biggest city, Blantyre, and Mzuzu in the north to quell the protests.
The president accused the protesters of committing treason.
"If you go back to the streets, I will smoke you out. Enough is enough," Mr Mutharika said, after naming six of the organisers in a speech to policemen.
They include Mr Hajat, the director of the Institute for Policy Interaction advocacy group, who told the BBC from an unknown location that he feared for his safety.
"My wife and children are distraught. They are worried about my security and theirs. Nobody is staying at home," he told the BBC's Network Africa programme.
"My mother had a triple bypass. She has aged 10 years in the last few days."
Mr Hajat said the Acting Executive Director of the Malawi Human Rights Consultative Committee, McDonald Sembereka, was also in hiding while he understood that the group's chairman, Undule Mwakasungula, had fled Malawi.
He said that the activists would not be intimidated and would organise further protests if their demands were not met.
"We are challenging a very fundamental Malawian cultural perspective where you do not dare to challenge authority. We have done that. We have shaken the tree," he said.
Some of those who died last week were bystanders caught up in clashes between the security forces and demonstrators.
The BBC's Raphael Tenthani in Blantyre says the death toll has risen to 19 after a person injured in the violence died in Lilongwe on Sunday night.
The protests were the most violent since multiparty democracy was introduced more that 15 years ago, our reporter says.
Mr Mutharika reshuffled the military leadership on Sunday, replacing the long-standing commander of the army, Gen Marko Chiziko, before appointing him as his national security adviser, he says.
Civil groups called the nationwide protests after accusing Mr Mutharika of plunging Malawi into its worst economic crisis, with shortages of fuel, electricity and foreign currency.
They said they feared the country was turning into "autocratic kleptocracy".
Mr Mutharika - who was elected in 2004 - said he was prepared to enter into dialogue with the opposition but they should stop "sending your boys" on the streets to cause chaos.
The government passed an austerity budget recently, raising taxes to reduce dependence on aid.
Earlier this month, the UK cut aid to Malawi after accusing the government of handling the economy badly. Other donors have also reduced aid.
Malawi is one of the poorest countries in the world, with an estimated 75% of the population living on less than $1 (60p) a day.