Boris Johnson has hinted Saudi Arabia could speed up oil production to help calm spiralling energy prices for Britons, as he praised the country for improving its human rights record despite three more people being executed during his visit.

With pressure rising at home over a cost of living crisis compounded by western countries trying to end their reliance on Russian imports, the UK prime minister made a dash to the Middle East to urge leaders to help stabilise oil prices by ramping up supply.

Johnson said there was “a lot of agreement” in his meeting with Saudi Arabia’s ruler, Crown Prince Mohammed bin Salman, adding that efforts should be made to ensure “the global economy is not damaged by the current spikes”.

On the same day, the Saudi government executed three more citizens.

It came days after the largest state killing in the kingdom’s history of 81 men. The UN said half were Muslims from the Shia minority and had taken part in protests calling for greater political participation a decade ago.

Johnson’s visit was heavily restricted for media, with government sources claiming No 10 wanted to draw relatively little attention to it.

Though unable to announce any firm commitments after touring the Saudi Arabian and UAE capitals, the prime minister said he made the case for why oil producing countries should try to steady prices to avoid a 1970s-style energy crisis.

In a short interview afterwards, Johnson insisted there was “a lot of agreement that it is important to avoid inflation” and the “damaging economic consequences” that could follow.

Oil prices had been trading at a 14-year high of close to $130 a barrel after Russian president Vladimir Putin’s decision to invade Ukraine. However, the price slid to about $100 on Wednesday amid continuing ceasefire talks.

Johnson was pessimistic that he would be able to open up the spare capacity of the Saudi-led Organisation of the Petroleum Exporting Countries (Opec) to soften the blow of divesting from Russian fossil fuels.

But he stressed the west needed energy independence and countries now realised they had made a mistake by building up dependence on Russian hydrocarbons, allowing Putin to blackmail nations and hold their economies to ransom.

Asked if he raised the recent mass executions, Johnson only said: “I always raise human rights issues, as British prime ministers before me have done, time after time. It’s best if the details of those conversations are kept private, they’re more effective that way.”

He claimed that “in spite” of the killings, “things are changing in Saudi Arabia” and added: “That’s why we see value in engaging with Saudi Arabia and why we see value in the partnership.”

The human rights charity group Reprieve said the three people killed – Bandar al-Zahrani, Hamid al-Osaimi and Muhannad al-Assiri – were all Saudi nationals accused of murder.

“By travelling to meet Mohammed bin Salman so soon after a mass execution, Boris Johnson clearly signalled that in return for oil, the UK will tolerate even the gravest human rights abuses,” Reprieve’s director Maya Foa said.

“Today’s executions are the immediate result. The prime minister has blood on his hands.

“Carrying out these executions while the leader of a western power is on Saudi soil was provocative act, designed to flaunt the crown prince’s power and impunity to the world.

“It is not acceptable to cite Russia’s war crimes to try to justify trading blood for oil elsewhere. It shows the world we will apply double standards for our convenience, and embolden countries like Saudi Arabia into further atrocities, just as Putin was emboldened by our willingness to take his cronies’ cash for decades.”

Saudi Arabia is one of 38 countries still to use the death penalty and Salman is believed by US intelligence to have ordered the murder of the journalist Jamal Khashoggi in 2018.

Despite Johnson’s tough talk about taking action against authoritarian regimes, he had been criticised before the trip by Keir Starmer. The Labour leader said that “going cap in hand from dictator to dictator is not an energy strategy”.

Julian Lewis, a Conservative MP who chairs parliament’s Intelligence and Security Committee, also called on the government to ensure that “in seeking to lessen our dependence upon one source of oil and gas, we do not end up creating a source dependency on another unreliable and sometimes hostile regime”.