THERESA May dined with the Saudi monarch last night after insisting she is “engaging” with Gulf states on human rights – on the day 15 people were sentenced to death on spying charges.

The court in Saudi capital Riyadh imposed capital punishment on 15 people said to have been involved in espionage for Iran, with another 15 people given jail sentences from six months to 25 years long.

All were detained in 2013 and went on trial in February, and the death sentences will now be passed to the King for ratification. Those condemned to death include members of the country’s minority Shia Muslim community.

The news, reported by the Arabic-language al-Riyadh newspaper, came as May takes part in a two-day visit to Bahrain for the Gulf Co-operation Council summit.

However, campaigners including Human Rights Watch have expressed concerns over the “deteriorating human rights situation” in host nation Bahrain and hit out at the UK’s “abject failure to exert any positive influence” on leaders in the region.

Yesterday, May said: “If we look at this issue, it’s important that we see there isn’t an ‘either or’. While we talk about trade, we also talk about human rights issues.

“What is important, if you are going to raise these issues of human rights, if we are going to work to see that it is being addressed, is that we are engaging with these states, that we are here and we are talking to them, not that we are just sniping from the sidelines.”

The Prime Minister, who wants to “turbo-charge” UK relations with the region, is the first woman and first UK leader to attend the annual meeting of the Gulf Co-operation Council, members of which include Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates (UAE).

A letter to May signed by organisations including Human Rights Watch, Campaign Against Arms Trade (CAAT) and the Bahrain Institute for Rights and Democracy (BIRD), says there has been a “marked deterioration” in conditions in the host nation since the summer, when authorities dissolved the main political opposition group al-Wifaq and jailed prominent human rights activist Nabeel Rajab, who remains in custody and has been denied bail.

It states: “Your status as the guest of honour at this summit is a clear reflection of the close alliance the UK government now enjoys with the government of Bahrain and the other Gulf Cooperation Council states.

“If your government is serious about its commitment to encouraging reform and dialogue, you should use this influence to press the government of Bahrain to put an immediate stop to this repression.”

Doha News, one of Qatar’s only independent news outlets, was blocked to local users at the end of November, with the company blaming authorities for “an act of censorship”, while criticisms over the UK’s role in arming the Saudi offensive in Yemen continue, with a judicial review brought by CAAT to be heard in February.

The campaign claims arms sales to the country breach both UK and EU weapons export laws.

The UK is also accused of failing to act on claims by 43 British citizens of torture or mistreatment within the UAE justice system between June 2010 and June 2015, and has been asked to intervene in the case of Bahraini prisoner Mohammad Ramadan, who was sentenced to death in 2014 and has exhausted all appeals.

His wife Zainab Ebrahim claims a UK-backed ombudsman failed to support her husband and hit out at Britain, stating: “The UK Government has championed Bahrain’s supposed human rights reforms, spending millions coaching a torture watchdog, training hundreds of guards at the death-row jail where he is held, and secretly assisting Bahrain’s police, who torture peaceful protesters.”

BIRD’s Sayed Ahmed Alwadaei said: “The Prime Minister should use her position in Bahrain to condemn today’s death sentences in Saudi Arabia and call for the release of Mohammad Ramadan and innocents like him. To do any less will be to open a new era of British complicity in human rights violations.”