WASHINGTON - US President Barack Obama issued an executive order on Monday, imposing additional sanctions on some Venezuelan officials over human rights abuses and corruption.

The order bans seven Venezuelan individuals from entering the United States, freezes their assets in the US and prohibits Americans from doing business with them. The individuals are all incumbent or former officials from Venezuela's security apparatus.

"The situation in Venezuela...constitutes an unusual and extraordinary threat to the national security and foreign policy of the United States, and I hereby declare a national emergency to deal with that threat," Obama said in the executive order, accusing the Venezuelan government of violating human rights, curtailing press freedom, and exacerbating public corruption.

US Congress passed last year legislation that levies sanctions against some Venezuelan officials, targeting those who directed "significant acts of violence or serious human rights abuses" against protesters during anti-government demonstrations earlier that year. The protests that started from February resulted in more than 43 people dead and over 800 injured.

"We are deeply concerned by the Venezuelan government's efforts to escalate intimidation of its political opponents," White House spokesman Josh Earnest said in a statement on Monday. "Venezuela's problems cannot be solved by criminalizing dissent."

He called on Venezuelan government to release all political prisoners, including dozens of students, and to improve the climate of respect for human rights and fundamental freedoms.

Washington and Caracas have had a tense relation since late president Hugo Chavez took power in 1999. The two countries have not exchanged ambassadors since 2010 with constant accusations.

"Despite the difficulties in our official relationship, the United States remains committed to maintaining our strong and lasting ties with the people of Venezuela and is open to improving our relationship with the Venezuelan government," Earnest said.