ISLAMABAD - According to a comprehensive United Nations survey on drug use in Pakistan, some 6.7 million people, or 6 percent of the population, used drugs at least once in 2013. The use of illicit drugs is affecting the South Asian nation.

Drug use is on the rise in Pakistan. And it's not just heroin addicts.

Pakistanis of all ages are using everything from hashish to tranquilizers to opiates, according to the United Nations Office on Drugs and Crime.

The UNODC's Cesar Guedes said drug use was most prevalent in the 25 to 39 age group.

"Guess what? That is the most productive age group in the country, the work force in the country.  And this is a matter of concern because it is there where the use of drugs is most concentrated," said guedes.

Pakistan is at the crossroads of opium-producing Afghanistan and countries producing the chemical precursors needed to manufacture illicit drugs.

Which means drugs are becoming cheaper and more available. More than four million Pakistanis are now drug dependent.

Mohammed Shahid, the director general of the monitoring unit of Pakistan's narcotics control division, said there was another worrying trend.

"There is an alarming increase in the injection, people who are using drugs through injections," he said.

There are now 430,000 regular intravenous drug users. This has led to a rapid increase in the spread of the HIV/AIDs virus.

"This is a very difficult piece of news to convey to all of you - Pakistan is among the 15 countries with the highest prevalence of HIV/AIDS among injection drug users," said Guedes.

Roughly half of the injecting drug users are HIV positive and actively transmitting the disease.