San Francisco, Nov 17 (DPA) Networking giant Cisco Systems Monday raised its offer to buy Norwegian video communications company Tandberg by 11 percent - to $3.41 billion - after the company's previous bid failed to win sufficient support from Tandberg shareholders.

Cisco said that the bid was its last offer and required 90 percent of Tandberg shareholders to accept the deal by Dec 1 or it would be withdrawn.

Some 40 per cent of Tandberg shareholders had accepted the previous bid which was tendered last month. That all-cash deal represented an 11-percent premium on Tandberg's closing price and was recommended unanimously by Tandberg's board.

The possible deal would represent Cisco's first purchase of a public company outside the US.

The deal underscores Cisco's long term goal of dominating the market for online video conferencing technology, which Cisco Chairman and Chief Executive Officer John Chambers described as a $34-billion market 'and rapidly growing'.

Cisco already has a successful line of high end video-conferencing known as TelePresence systems. Tandberg offers smaller-sized, cheaper systems and specialized software for managing video conferencing systems and for creating connections between systems that rely on different underlying technologies.

'Cisco and Tandberg have remarkably similar cultures and a share dvision to change the way the world works through collaboration and video communications technologies,' said Chambers. 'Collaboration is a $34-billion market and is growing rapidly. This acquisition showcases Cisco's financial strength and ability to quickly capture key market transitions for growth.'