Turkish police investigating a mass alcohol poisoning last month have made 22 arrests and seized thousands of bottles of bootleg liquor.

A clandestine factory was reportedly found where methanol was being used to make counterfeit alcoholic drinks.

Four Russian tour guides died and some 20 fell ill after being served tainted alcohol on a yacht near the resort of Bodrum.

The deaths of the guides, mostly young women, made headlines in Russia.

According to Turkish news agency Anatolia, arrests were made in four different regions of the country.

In the southern province of Mersin, 7,000 bottles of bootleg liquor were found along with empty bottles, stickers and other materials used in production.

Police reportedly found methanol, commonly used to mix bootleg alcohol, in whiskey on the yacht.

Turkey's agriculture ministry said earlier that the alcoholic drinks served on the yacht had been imported by an Ankara company from North Cyprus and distributed to Ankara, Mersin, Antalya and Mugla.

'Strange taste'
The latest victim, a Russian man, died on Monday in hospital in western Turkey.

Two of the other victims also died in Turkey and the third after flying back to Moscow.

Twenty Russians and one Turk were affected, and one woman has been in a coma.

The party of some 60 Russians was largely made up of travel agency managers, in Turkey for a fact-finding visit, the Russian newspaper Argumenty i Fakty reported last week.

Anatasia Lavrenko, whose friend Marina Shevelyova died in Moscow, told Russian online newspaper Life News they had paid $50 for the night-time cruise and each had been served between 10 and 12 of their favourite cocktails, whiskey and cola.

"Sometimes it seemed like the taste of the alcohol was too strong but then I thought the barmen had simply poured out too much whiskey and I did not attach any importance to it," she said.

Life News published on its Russian-language website a photo said to show the two young women drinking aboard the yacht.

The day after the cruise, when they were due to fly home together, both women woke up feeling ill but blamed a hangover.

However, Ms Shevelyova became more and more sick on the flight back and, after being rushed to hospital in Moscow, died last Tuesday.