Further fare increases on the region's trains could provoke a day of national fare strikes, a passengers' campaign group has warned.

More Train Less Strain (MTLS) said rail travellers' "patience is near to breaking point" after the latest round of ticket price hikes came into force earlier this month.

Passengers were faced with a six per cent rise on Government-regulated fares based on the rate of inflation, while other fares set by First Great Western went up by 6.6 per cent.

MTLS spokesman Tony Ambrose, who arranged a high-profile strike over fares this time last year, said the rises could not be justified.

And he told the Bristol Post he had been in touch with similar organisations from around the country, which are equally dismayed at the continued rise of rail fares.

Thousands of commuters in Bristol and Bath took part in the fare strike last January, refusing to pay for tickets in a protest against constantly late and overcrowded trains.

Mr Ambrose said his group would be prepared to lead a national demonstration against any further fare increases, which he believes are an unfair tax on rail passengers.

He said: "More Train Less Strain warns the Government that whilst commuters may quietly put up with appalling conditions and outrageous fares on a daily basis, their patience is near breaking point.

"Our previous fare strikes have demonstrated that, when organised, commuters can speak with a very loud voice indeed.

"If need be, we will play our part to mobilise hundreds of thousands of commuters and organise a national day of action on the railways, that will bring our concerns to the doorstep of every MP.

"First continues to be one of the country's most profitable companies and these fare hikes will ensure that their shareholders continue to cream off the companies profits.

"In addition, the Government stands to benefit from this tax on rail commuters as their policy is to reduce their subsidy to the rail industry year on year, and generate a higher proportion of the rail industry's costs from passenger revenue.

"Government policy on railways has hit the buffers and needs a rapid overhaul.

"It is a short-term policy with no other aim than generating the maximum income from rail users for a minimum level of service.

"It will drive people away from the railways at a time when every other European country is investing in the railways for the long term in a bid to attract more passengers from cars and short haul flights.

"This is a warning to First and all train companies that commuters are a force to be recognised and that we won't put up with this for much longer."

Responding to complaints about this month's fare rises when they were first announced, a First Great Western spokesman had said that not all fares were going up and more than 80 per cent were discounted or price-capped.

He said the proceeds of price rises would be ploughed back into major investment projects to boost network capacity.

The spokesman said: "Many of our industry's costs are rising at above-inflation rates.

"We had little choice but to increase some of our fares.

"This is also our first increase since January 2008.

"The majority of other rail companies raised their fares in May and September last year as well."