The bosses of Britain’s “big five” retail banks have been summoned to a meeting with the chancellor, Rachel Reeves, this week to discuss how to limit the economic impact of the crisis in the Middle East triggered by the US and Israel’s attacks on Iran.

The chief executives of HSBC, Barclays, Lloyds, NatWest and Santander have been asked to attend an emergency summit that comes amid increasing acceptance that a major economic hit from the Iran war is unavoidable.

Talks will focus on how to protect those most vulnerable to the ripple effect, according to Treasury sources, with borrowers who are braced for mortgage rate increases a particular area of focus.

This will include an update on banks’ commitment to support 1.6m customers whose fixed-rate deals end between now and the end of the year, under the government’s mortgage charter. Lenders have already written to customers in that position, outlining their options.

Soaring energy prices in recent weeks, after Iran retaliated to US and Israeli strikes by closing the strait of Hormuz shipping route and attacking oil-producing neighbours, have sparked gloomy forecasts about rising inflation and mortgage costs.

More than 1 million UK households could see the cost of servicing loans on their homes increase, the Bank of England has predicted.

In that scenario, the forbearance of major mortgage lenders could be key to preventing a huge shock to the economy.

The meeting, first reported by Sky News, could also see banks asked to offer an early insight into how consumers are behaving in response to the unfolding crisis.

Jitters caused by the conflict in the Middle East have already resulted in banks pulling about 1,500 mortgage products, with many raising interest rates on their remaining 7,000 home loan products, the Bank’s financial policy committee said earlier this month.

The increases, named “Trumpflation” after the US president, have put pressure on households preparing to sign on to new mortgage contracts, with the Bank now forecasting that about 5.2m borrowers – or roughly 58% of borrowers across the country – could face higher mortgage payments by the end of 2028.

The meeting comes as banks are finalising their end-of-year results, which are likely to include revised outlooks for the UK economy.

The Guardian has approached the Treasury and the banks for comment.