Tehran, Iran: Iran will help couples meet the cost of infertility treatment as the government tackles a growing crisis that has seen millions of couples failing to conceive, the government announced Tuesday. 

"As of today, all infertile Iranian couples, who number about two million couples, can enjoy the coverage of their expenses," ISNA news agency quoted deputy health minister Mohammad Aghajani as saying.

State insurance will cover 85 percent of the costs, he said -- the first time infertility treatments have been covered -- and the government has allocated around $30 million (27 million euros) for the project. 

Experts believe infertility has been on the rise in Iran, and say Iran's worsening pollution is a key cause. 

A study in 2012 found that 20 percent of couples were failing to conceive after trying for a year -- putting the country around five to eight percentage points higher than the global average reported by the World Health Organization.

Supreme leader Ayatollah Ali Khamenei has called for efforts to increase the population, currently 80 million. 

In recent years family planning budgets have been cut and prevention methods like vasectomies have been banned.

A growing number of clinics offer in-vitro fertilisation (IVF) -- fertilising a sperm and an egg in a lab -- but a cycle of treatment can cost around $2,000, around five months' wages for the average worker, and success is not guaranteed.

Iran has a broadly progressive attitude to modern medicine, and some of the most advanced facilities in the Middle East, but such treatments remain a sensitive issue. 

As well as social taboos, Iranians must contend with varying instructions from religious leaders.

It is illegal, for instance, to directly insert into a woman the sperm of a man who is not her husband.

Using another woman's eggs is less controversial, although a "temporary marriage" is recommended between the man and female donor that can be annulled after the operation.

There is a grey area, however, since some clerics say an egg that has already been fertilised in a lab -- even with a third party's sperm -- is considered to have its own identity and can therefore be implanted into the womb.