By Max Colchester And Jason Douglas 

LONDON--The U.K.'s biggest banks will be subjected to a severe global economic slowdown and face major difficulty trading assets under the latest Bank of England stress test.

The hypothetical stress test sees the eurozone and Chinese economy contract, commodity prices fall and banks wrestling with the default of a handful of major trading partners, the Bank of England said Monday.

Seven major British based banks must maintain a ratio of core tier one equity to risk weighted assets of 4.5% to pass the test. They must also keep a leverage ratio of above 3%. The results of the stress test will be published in December. Banks that fall short may have to raise equity or further shrink their balance sheets.

"This year's test will have a different focus and is equally important," said Mark Carney, Bank of England governor. He added that the balance sheet check will help spot additional vulnerabilities in the system.

Unlike last year's test, which focused on a U.K. property bust, this five-year scenario is aimed at seeing how U.K. banks with big global operations and investment banks handle a world wide economic downturn and financial market crunch. This will put pressure on banks with big international operations including Barclays PLC, Standard Chartered PLC and HSBC Holdings PLC.

One key aspect of the test will be how banks cope with an inability to sell assets in slow down. This reflects regulators' concerns that a loss of trading liquidity in markets could pose a real threat to financial stability. Banks will be asked to model how they would deal with five major trading counterparties going bust. All banks are expected to grow lending to the U.K. economy despite the slow down.

The banks being tested are Royal Bank of Scotland Group PLC, Barclays PLC, HSBC Holdings PLC, Lloyds Banking Group PLC, Nationwide Building Society PLC, Santander UK and Standard Chartered PLC. Unlike last year the Co-operative Bank won't feature in the test, as it has shrunk its balance sheet and become less critical to the U.K. financial system.

The stress test assumes a sharp slowdown in global economic activity that begins this year and lasts until 2019. The global economy ekes out growth of 0.9% in 2015 hit by combination deflation pressures, a Chinese housing price collapse and a big selloff in financial markets. The scenario doesn't assume that Greece leaves the eurozone but does assume a sharp contraction in the euro area economy.

Write to Max Colchester at max.colchester@wsj.com and Jason Douglas at jason.douglas@wsj.com

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