LONDON, Oct 30 (Reuters) - Britain invited the private sector to play a bigger role in plans to ease congestion of the UK's clogged transport network on Tuesday while keeping a lid on CO2 emissions.

The transport department reiterated its support for airport expansion in southeast England, and said it would look at ways to speed up motorways and rail links between England's three biggest cities, London, Birmingham and Manchester.


It said that while most of its funds had been earmarked to 2014, it had 20 billion pounds ($41.3 billion) still to allocate in the five years to 2019.

"We believe that there is further potential, as yet untapped, for involving the private sector in improving Britain's public transport systems and networks," said the report "Towards a Sustainable Transport System".

The paper raised the possibility of widening motorways, congestion charging schemes in towns and cities, and expanding Britain's high speed rail.