Citing a growing "drug glut" throughout the United States, a senator is convening hearings here Monday to find out why the federal government has been unable to stem the influx of narcotics into this country.

Voicing his "true frustration" at the rising tide of heroin use and related crime, Sen. Dennis DeConcini (D-Ariz.) said last week that his Senate Appropriations subcommittee on state, justice, commerce and the judiciary "has already accumulated some convincing evidence that the illicit drug trade in America is at an all-time high."

"It appears that drug-related deaths are up nationwide, the amount of heroin entering this country from Southwest Asia is enormous, and federal and local law enforcment officials are finding it almost impossible to keep up," DeConcini added.

Sources close to the subcommittee say staff investigators, reports and data from the General Accounting Office points to continuing heroin and drug problems in the Southwest, and an influx of extremely pure white Asian heroin on the East Coast.

One report for the subcommittee staf states authorities in New York City are purchasing "extremely high" quantities of white Asian heroin on the street from children as young as 11, 12 and 13 years old.

The staff report says "Italian organized crime families" in New York are attempting to regain control of the heroin distribution network on the East Coast from black and Hispanic dealers who are switching to the equally profitable cocaine trade.

The report also said heroin now being sold in New York City is so pure -- three to five times as pure as what addicts have been accustomed to in recent months -- that "there may be an epicemic of heroin overdose deaths."

At least some of the information in the staff report has been confirmed by drug abuse experts in New York state.

"The supply of heroin is greater (since last fall) and the heroin stronger and the price cheaper than any time in the last 20 years." Julio Martinez, the director of drug treatment and prevention programs in New York state, said recently.

The DeConcini report indicates that heroin is entering New York City "via an extremely circuitous route" that begins in Southwest Asia and continues to Hawaii and California before being transported across the country.

The staff report challenges federal Drug Enforcement Agency claims that the heroin battle is being won over the years through reduced purity and higher prices.

In the Southwest, data made available to the subcommittee staff show heroin purity and drug overdoses have decreased, but that other drugs remain highly available and many addicts are supplementing heroin with other illegal substances and some legal ones like alcohol.

Another problem in the Southwest, DeConcini says, is that DEA and other federal agencies like the U.S. Border Patrol and Customs Service are not coordinating their efforts well.

Much of the information being compiled by the subcommittee supplements the findings of a report issued by the GAO in October 1979.

That report said the DEA and other federal agencies had made "some positive results" in reducing heroin supplies but that the drug trade "continues to flourish" because of constantly changing drug distribution and trafficking patterns.

"Federal supply reduction efforts have not had a significant impact on the overall drug problem," the GAO concluded.

DeConcini, who is calling for creation of a "drug czar" to coordinate federal drug control efforts, says his cubcommitee is not trying to "destroy any agency, including DEA."

Nevertheless, the hearings are likely to focus additional criticism on DEA. They also may aid DeConcini in what his staff says is a long-shot effort to have the Senate appoint a select committee to deal with organized crime and narcotics problems.