A high-ranking Nicaraguan Justice Ministry official has fled the country with his family, charging that communists are running the Sandinista revolutionary government.

Nevardo Arguello, who appeared yesterday at a news conference sponsored by the American Security Council, said he drove his car past armed border guards without stopping to go through customs because he had been told he was under investigation and could not leave the country.

Arguello, 33, described himself as the third-ranking official in the Justice Ministry and said he had been "fighting within" the ministry to "end communism" and prevent "injustices" in the confiscation of property.

Nicaraguan Ambassador Rita Delia Casco said Arguello was under investigation for misusing his position to return confiscated property to its owners.

Arguello, who is the highest ranking official to defect for political reasons, said many others are planning to do the same.

The Reagan administration's accusations that Nicaragua is supplying arms to El Salvador has increased tension in Nicaragua and aggravated polarization between the more radical Sandinistas and their middle class allies in the business community.

Appearing with Arguello at the news conference was Jose Francisco Cardenal, a businessman who fled Nicaragua shortly after being named vice president of the legislative Council of State. Another official who left the government and went into the opposition is former defense minister Bernardino Larious who was convicted and jailed last year on charges of plotting against the government.