21 February 2013 Last updated at 03:52 ET By Sean Coughlan BBC News education correspondent

One of the emerging giants among online universities has announced that it is signing up a further 29 universities, including institutions in the US, Europe and Asia.

Coursera, set up by academics from Stanford University, will now offer online courses from 62 universities.

There are 2.8 million online students registered, says Coursera.

Co-founder Andrew Ng said this was helping universities to "raise their impact both on and off campus".

Coursera, set up less than a year ago, has become one of the pace setters in the rapidly expanding field of online universities - often described as MOOCs (massive open online courses).

It provides an online platform for universities to offer courses for people to study from home.

Global reach

This latest crop of new recruits widens its reach outside the United States, with institutions including the Chinese University of Hong Kong, Ecole Polytechnique in France, Leiden University in Holland, Sapienza University of Rome in Italy, the University of Tokyo in Japan, National University of Singapore and the University of Geneva in Switzerland.

US universities joining the online platform include Northwestern, Penn State and Rutgers,

Another significant step was announced recently which will make Coursera's online courses count towards a full degree.

At present, such online courses might be as difficult as their campus-based versions, but most of them are not formally recognised as counting as course credits.

But a first group of five courses on the Coursera platform, including a genetics course from Duke University and algebra at University of California, Irvine, have been recommended for accreditation.

Sarah Eichhorn, from the University of California, Irvine's maths department, said this represented an "online education milestone" which would put such maths courses in reach of students around the world.

The accreditation of online courses raises questions about the impact on traditional campus-based courses, where a degree course in the US can cost more than $50,000 (£33,000) per year.

It will also raise questions about the charging structure of online courses, which in this pioneering stage have mostly been free or low cost.

Coursera intends to become a financially viable, profit-making university project - but raising income from internet traffic and add-on services, rather than directly charging users.

The rival edX online university project on the US east coast has been funded by the Massachusetts Institute of Technology and Harvard and is not for profit.

UK online project

There have also been developments in the UK's fledgling online university platform, Futurelearn, announced by the Open University last year.

Five more universities are joining Futurelearn - Bath, Leicester, Nottingham, Queen's Belfast and Reading.

The British Library is also going to develop online courses using material from its collections.

It means there will be 18 universities and institutions which intend to provide courses with Futurelearn.

Martin Bean, the Open University's vice chancellor and head of the Futurelearn project, has joined Prime Minister David Cameron's delegation to India, which has been trying to promote UK universities.

"We're in the middle of an exciting time for higher education in which anything is possible," said Mr Bean.

Coursera co-founder Daphne Koller said online university networks could "offer a high quality learning experience to anyone who wants it".

"One of our top priorities is to reach the people who need education the most, including those who would not otherwise have access."