LAGOS, July 2 (Reuters) - An eagerly-awaited submarine cable linking West Africa to Europe has gone live, paving the way for cheaper and more reliable internet access in one of the world's fastest-growing telecoms markets, its operators said on Friday.

The 7,000 km (4,350 mile) fibre optic Main One Cable runs from Portugal to Nigeria and Ghana, and also branches out to Morocco, the Canary Islands, Senegal and Ivory Coast.

The Main One Cable Company says it delivers more than ten times the broadband capacity of the South Atlantic Terminal (SAT-3), Nigeria's sole existing undersea cable, and 20 times the entire satellite capacity of sub-Saharan Africa.

"The ramifications of Main One's cable will be felt in all sectors -- from education, to health, to entertainment, helping drive economic growth and creating job opportunities all over Africa," the company said in a statement.

An expanding network and falling prices are expected to fuel explosive growth in mobile broadband in Africa over the next few years, particularly Nigeria, which has overtaken South Africa to become the continent's largest mobile telecoms market.

Internet connectivity in Nigeria, Africa's most populous nation of 140 million people with 5 percent broadband penetration levels, is expensive and unreliable and many business are forced to rely on satellite communications.

Enhanced capacity will bring more competition among big operators such as South Africa's MTN and India's Bharti, which last month completed a $9 billion acquisition of the African operations of Kuwait's Zain.

CATCHING UP

Main One's cable will also put Nigeria at par with the rest of the world in terms of internet and broadband services. The cable, which has a capacity of 1.92 terabits, has a speed which can accommodate 1 million MP3 downloads and 100 million voice calls per second.

South Africa has 1.28 terabits.

"Given the increase in bandwidth and the falling cost of accessing that bandwidth, it is really going to move West Africa and Nigeria into the 21st century," said Andrew Alli, Chief Executive Officer of the Africa Finance Corporation (AFC), which financed $37 million of the $240 million project.

"There now needs to be investment within Nigeria to take that capacity to the end-user."

There are around 10 undersea cables either under construction or in the planning stages around the whole of Africa. A second new fibre optic cable owned by Nigerian telecoms firm Globacom is also due to go live this year.