UPDATE 2-U.S. joins lawsuits against J&J over marketing

* U.S. DOJ joins lawsuits against J&J, Scios

* Suits accuse companies of marketing Natrecor off-label

* Company says reviewing allegations

* Shares close slightly higher (Adds company comment)

WASHINGTON, Feb 19 (Reuters) - The U.S. government is joining two lawsuits against Johnson & Johnson JNJ.N and its Scios unit, accusing the companies of promoting heart failure drug Natrecor for unapproved uses, the Department of Justice said on Thursday.

The drug is approved to treat patients with acutely decompensated congestive heart failure who experience shortness of breath. But DOJ officials said in a statement their investigation found Scios aggressively began marketing the drug to patients with less severe heart failure soon after its approval in 2001.

Those patients were given Natrecor as part of scheduled, outpatient infusions, the DOJ said.

By promoting a use not approved by the U.S. Food and Drug Administration, the companies “caused false and fraudulent claims to be submitted to the federal health care programs,” the DOJ said.

Medicare and Medicaid, the nation’s health insurance programs that cover the elderly, disabled and poor, are the largest payers of health care in the country.

“We have reviewed the allegations thoroughly and will address them in court,” Johnson & Johnson spokesman Ernie Knewitz said.

A panel of top cardiologists in 2005 told Scios to stop marketing Natrecor for the less severe use, according to the DOJ. The company later sent doctors a letter saying there was little evidence supporting such use and in 2007 released results from a clinical trial that showed no such benefits, it added.

Former Scios sales managers filed the two separate civil lawsuits under the False Claims Act, which allows whistle-blowers to give the government information about wrongdoing, the agency said.

The suits also make other allegations, but the government is only intervening with regard to the claims of off-label marketing, it said.

J&J shares closed 10 cents higher at $55.93. (Reporting by Susan Heavey; Editing by Andre Grenon)