LONDON: Strikes crippled Britain's rail network for the second day this week and staff at British Airways voted for a walkout on Thursday amid warnings the country was facing a summer of industrial discontent.

A spike in the cost of food and fuel is pushing many household budgets to the brink, driving trade unions to demand higher pay increases for their members. The government has urged wage restraint to avoid an inflationary spiral.

Britain's rail network was brought close to a standstill when 40,000 workers went on strike following a similar walkout on Tuesday, as union leaders, train operating firms and the government faced off over demands for pay increases to keep pace with surging inflation and a promise not to cut jobs.

Passengers have been advised not to use trains unless absolutely necessary all week with only about one in five services running. Unions warned of more action unless a deal could be reached.

"We'll continue to talk to the companies about everything that's been put on the table and we'll review that and see if and when there needs to be a new phase of industrial action," Mick Lynch, secretary-general of the Rail, Maritime and Transport Workers (RMT), told the BBC.

"But if we don't get a settlement, it's extremely likely that there will be."

Although talks are ongoing, a third day of strikes is planned for Saturday. Teachers, health workers and other industries are also moving towards industrial action in what unions say could be a "summer of discontent".

British Airways workers at London's Heathrow voted in favour of a walkout over pay, threatening to exacerbate disruption at Britain's busiest airport during an already chaotic summer for air travellers with the industry already struggling to cope with staff shortages.

The government has criticised the rail strikes, calling them counterproductive and most damaging for those on low incomes who depend on public transport and are unable to work from home.

"I think people should get around the table and sort it out," Prime Minister Boris Johnson said from Rwanda, where he was attending a Commonwealth meeting. "I want us to work together with the railway staff for a better future for the railway, and I think the strikes are a terrible idea."

Ministers are also planning to change a law that would make it easier for businesses to use temporary staff, in a move designed to minimise the impact of strike action. 

"Once again trade unions are holding the country to ransom by grinding crucial public services and businesses to a halt. The situation we are in is not sustainable," Business Secretary Kwasi Kwarteng said.

"Repealing these 1970s-era restrictions will give businesses freedom to access fully skilled staff at speed, all while allowing people to get on with their lives uninterrupted to help keep the economy ticking."