Chancellor Philip Hammond has been accused of putting trade above human rights during his tour of the Middle East.
His two-day Gulf visit is an attempt to bolster economic ties and forge investment opportunities post-Brexit.
But Amnesty International said he should be pressuring leaders into bringing an end to the conflict in Yemen, and reconsidering UK arms sales to Saudi Arabia.
Lucy Wake of Amnesty said: “Philip Hammond shouldn’t confine himself to trade issues during his Gulf visit, but should insist on a few human rights home truths with his hosts.”
It is the third time in four weeks a senior member of the Government has travelled to the region on a charm offensive. Prime Minister Theresa May and Foreign Secretary Boris Johnson visited late last year.
Mr Hammond met the acting prime minister of Kuwait and held talks in the United Arab Emirates with the Abu Dhabi National Oil Company, Abu Dhabi’s biggest sovereign wealth funds and Qatar’s largest banks.
The three countries all back Saudi Arabia’s support for the Yemeni president, whose troops are fighting Houthi rebels. Ms Wake said: “Top of his agenda must be the appalling loss of civilian life in Yemen, a conflict that Kuwait, Qatar and the UAE are all party to and one which the UK is effectively involved in with its massive arms shipments to Saudi Arabia.”
Human rights group Reprieve said the UK should raise Kuwait’s extension of the death penalty to 16-year-olds. Director Maya Foa said: “Trade must not be allowed to trump human rights.”