The river Thames is to get a free Wi-Fi network after two companies, namely free-hotspot.com and MeshHopper partnered up to launch what they claim is Europe's largest free metropolitian Wi-Fi network.

The 802.11g mesh network, officially known as "online-4-free.com", is situated along a 22-kilometre stretch of the Thames from Millbank to Greenwich, although this will be expanded to 36 kilometres in August.

The network is administered and run by MeshHopper, a UK company that provides Wi-Fi technology and networks. MeshHopper partnered with free-hotspot.com, after the UK company experienced a dramatic decline in the number of users when it switched off the free element of its network.

"MeshHopper realised they needed to offer a free component alongside their paid service," said Joe Brunoli, vice president of HotSpot Market Development at free-hotspot.com, an Irish website that directs users to free Wi-Fi hotspots around the world.

The online-4-free.com network is free of charge to users, providing they sit through a 15 to 30-second advert in return for 15 minutes free wireless access. At the end of 15 minutes, the user may continue in free mode, in which case they must watch another advert, or they may opt to purchase a subscription for access without adverts.

There is no time limit for the free access, Brunoli said, although they will just have to watch an advert every 15 minutes.

There are estimated to be 250,000 residents and 21 million visitors to the MeshHoppper network area every year. In addition, approximately five million people travel on the Thames annually, and there are approximately two million workers along the river.

The network will be available on the riverside, bridges and boats on the Thames.