I see no reason whatsoever why the state or anyone else should interfere with what parents seek for their family

Alan Masterton

But US researchers claim their method of spotting sperm which will produce a female embryo is accurate on nine out of 10 occasions, making it more reliable than other treatments.

Their claim has reignited concerns that the technology could be abused by people wanting to determine their child's sex for purely social reasons.

But Mr Masterton told BBC Scotland: "I see no reason whatsoever why the state or anyone else should interfere with what parents seek for their family.

"If they think this process would help them and their family I see no problem with that.

Alan Masterton: "It affects no-one else"

"If a family has four boys or four girls and they wish a child of the opposite gender to complete their family I see no problem with that.

"It affects no-one else."

Mr Masterton also told BBC Scotland that gender clinics which claimed to be able to help parents choose the sex of their baby were already operating in Britain.

"There are three centres here in the UK. The last one opened in Glasgow about three weeks ago," he said.

"A very similar process is available right now."

Different technique

The procedure is not regulated by the Human Fertilisation and Embryology Authority (HFEA).

However, a spokesman confirmed: "We do believe that there are three in operation."

It is believed that these clinics use a different technique, which was pioneered in the 1970s by Dr Ronald Ericsson.

The US researchers' work - which is said to offer a greater success rate - was presented to the European Society of Human Reproduction and Embryology congress in Lausanne on Wednesday.

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The MicroSort technique has been developed at the Genetics and IVF Institute in Fairfax, Virginia.

Dr Harvey Stern said the device was currently undergoing a clinical trial, but experiments so far had been highly successful.

The new technique involves separating out sperm which will produce a female embryo, which carry less genetic material than those which will produce males.

US researchers say that their technique could help couples to avoid passing on genetic illnesses which usually affect only boys.

Eminent British fertility expert Lord Winston warned parents against using the Fairfax procedure, which he said could cause damage to the unborn child.