Raman devices have not worked with some bottles in the past

A study published in the journal Analytical Chemistry said the new laser technique could examine the contents of blister packs and bottles.

A company will develop applications of the technique.

A spokesman for the Association of the British Pharmaceutical Industry (ABPI) said: "This is something we will watch with interest".

Raman spectroscopy - a technique which analyses changes in laser light bouncing off molecules to indicate their chemical composition - is already used to identify the chemical composition of samples and can be used with battery-operated hand-held instruments.

Investigate

However, it does not always work through some forms of packaging, and has not been feasible with non-transparent plastic bottles until now.

But in the Analytical Chemistry paper, Doctors Charlotte Eliasson and Pavel Matousek from the Rutherford Appleton Laboratory, run by the Council for the Central Laboratory of the Research Councils (CCLRC) said the new technique - called Spatially Offset Raman Spectroscopy (SORS) can investigate the contents of blister packs and plastic bottles without opening them.

SORS involves changing the alignment of the laser instrument so that light is gathered from areas away from where the laser hits the sample.

This shows up the chemical composition of the drugs - meaning that experts can see if their make-up is correct or not.

In a report on SORS last year, a team of scientists including some from Rutherford Appleton, and ICI said it could be used to identify "substances beneath surfaces" and foresaw its use to analyse the internal composition of bones and tissues, jewellery and industrial materials.

World Health Organization statistics indicate that 30% of medicines supplied in developing countries are fake; in some East European countries the proportion is 10%.

Spot-checks

"We're always looking at new ways of combating counterfeiting," an ABPI spokesman said.

In developing countries the problem was rife, he said - adding that the main risk in the UK arose from medicines bought without prescription on the internet.

The government's Medicines and Healthcare Products Regulatory Agency (MHRA) says it operates Europe's largest scheme of spot-checks on medicines, but adds: "It is recognised that no supply chain is impenetrable."