Two European firms are hoping to cash in on the age-old maxim that sex sells.

Private Media, a Barcelona-based broker of pornographic TV content, announced it had hired Germany's Commerzbank to explore the possibility of a European stock market listing.

The firm, which supplies hardcore pornography in 35 countries, is already listed on the Nasdaq exchange in New York, and is believed to be aiming primarily at Frankfurt's Neuer Markt.

Separately, T-Online, Europe's biggest internet service provider and a subsidiary of Germany's Deutsche Telekom, said it was considering offering erotic content on its proprietary webpages in an attempt to attract more traffic.

"You can make a lot of money with erotica," said Thomas Holtrop, T-Online's chairman, in an interview with FT Deutschland.

T-Online has so far had a policy of barring pornographic content.

A recent survey found that one-third of German internet users regularly visit pornographic sites.

Two years ago, Beate Uhse, a German sex merchandise firm, floated on the Neuer Markt.

The firm's choice of Commerzbank as financial adviser is significant.

The German bank has taken part in many of Europe's biggest porn-related corporate deals, including the Beate Uhse flotation.

These are buoyant times for the pornography business, which has profited from the rise of new media such as the internet and digital TV.

So far, dealers in pornography have been among the few firms able to profit from charging money for online content.

Both Beate Uhse's and Private Media's shares have gained by about 30% in value over the last three months.

And earlier this week US Playboy Enterprises made its first venture into hardcore erotica, paying $70m for three pornographic TV networks.

Playboy's shares bounced up by 12% on the news that it was abandoning its soft-porn-only policy.

The size of the global pornographic industry is traditionally estimated at an annual $20bn (£14bn), but is likely to be significantly higher.