Travellers are braced for major disruptions this week in their commuting as the biggest rail strikes in almost 30 years is due to start on Monday night.

British transport secretary Grant Shapps has condemned planned rail strikes as a “huge mistake” that will stop people from attending hospital appointments, sitting school exams or getting to work.

The action this week comes as British airports experience chaotic delays and last-minute cancellations and as many Britons also face a huge backlog at the office which processes passports.

It also highlights pressures on British households, which are experiencing the biggest cost-of-living squeeze since the 1950s, with rail workers saying they are facing cuts in the value of their pay at a time when inflation is spiralling.

Responding to criticism that the government should step in to try to force an agreement and prevent a strike, Shapps said on Sunday it was for the employers to negotiate with their workers.

“I think this is a huge mistake, unfortunately the unions … have been gunning for this strike throughout,” Shapps told Sky News. “It is disastrous, and it’s no way to behave on the railway.”

More than 50,000 rail workers will strike on June 21, 23 and 25 in a dispute over pay freezes and job cuts in what the Rail, Maritime and Transport Workers (RMT) union has billed the biggest industrial action in the sector in more than 30 years.

Mick Lynch, general secretary of the RMT, said his union was just looking for a pay rise that reflects the cost of living, but said train operators were making offers “nowhere near that” and he feared thousands would lose their jobs.

The main opposition Labour Party said the government should get involved in the negotiations to try to find a solution.

“This is a government that in 2019 came to power on a promise to level up,” Labour’s policy chief on tackling regional inequalities, Lisa Nandy, said, referring to a stated objective to reduce regional economic imbalances.

“Instead, what they have presided over is absolute chaos, chaos at the ports, chaos on the railways, chaos at airports, chaos everywhere you go, and that is because this is a government that is not doing its job.”