The United States on Friday slapped sanctions on another son of Nicaraguan President Daniel Ortega, accusing him of using a public relations firm to spread propaganda.

Juan Carlos Ortega joins both his father and mother, Vice President Rosario Murillo, and two of his brothers who are already on the US blacklist.

The Treasury Department also imposed sanctions on close Ortega aide Jose Jorge Mojica and two companies run by Juan Carlos Ortega including Difuso Comunicaciones.

It said the company spreads "propaganda" for the leftist government and has engaged in money laundering, which formed the legal basis for the sanctions, which freeze any assets in the United States.

"The United States will continue to target those who prop up the Ortega regime and siphon money from the Nicaraguan economy," he said.

President Donald Trump's administration has been ramping up pressure on Nicaragua in line with its efforts to fight its regional allies Venezuela and Cuba.

A leader of the left-wing Sandinista movement, Ortega, 74, was re-elected in disputed polls in 2016 for a term that ends in 2022.

But mass protests broke out in 2018 calling for earlier elections after Ortega attempted social security reforms that would trim benefits.

At least 328 people died as security forces put down the protests, according to the Inter-American Commission on Human Rights.