David Cameron's Gulf mission is a conspicuous attempt to calm relations with Saudi Arabia and the United Arab Emirates, both vital trading partners, after spats caused by the changes during the Arab spring and fears over the growing strength of Islamist groups in the Middle East.

The trip is part of an ongoing effort to smooth recently ruffled feathers in the two autocratic states and ensure that billions of pounds worth of defence sales and other UK economic interests are not affected.

Problems on the prime minister's agenda include sudden difficulties over renewing a key BP oil concession in Abu Dhabi, the largest of the Arab emirates, and worries about a £7bn fighter aircraft deal with Saudi Arabia. Both countries are bristling over criticism of their human rights records – though little of it is from the British government. UK trade with the Gulf is worth £17bn a year.

Cameron's trip was arranged some time ago, but follows last month's extraordinary outburst by the Saudi ambassador to London, who said the kingdom felt "insulted" by a planned parliamentary investigation into Britain's relations with Saudi Arabia and Bahrain. Saudi sources warned the BBC that there could be a retaliatory "review" of the country's ties with the UK. British officials have subsequently been scrambling to explain that the government cannot control the Commons foreign affairs committee.

One view was that the ambassador may have been covering his back, rather than acting with the authority of the foreign minister, Saud al-Faisal, who has been ill.

Saudi officials complained that the foreign affairs committee had been "manipulated" by members of the vocal Bahraini opposition, some of them with links to Iran, who are keen to stress the Saudi role in helping to crush the unrest in Bahrain in March 2011.

Friends and critics of Saudi Arabia agree that the parliamentary move had damaged the country's already poor image in the UK. William Hague, the foreign secretary, and Philip Hammond, the defence secretary, are planning separate Gulf tours.

Compounding tensions with the Saudis is what regular visitors describe as a sense of drift in Riyadh, where 88-year-old King Abdullah is ailing, reforms are moving at a glacial pace and the future is uncertain. Another part of the problem is a London embassy that is notoriously prickly and uncommunicative.

Little damage has been felt so far, but there is palpable nervousness regarding the future. Cameron will push for the completion of the BAE Systems deal for 72 Typhoon jets, maintenance and missiles, and for lucrative business with the UAE, where the defence manufacturer has "huge ambitions," in the words of its chairman Dick Olver.

"The Saudis will play Russian roulette with payments which could be quite exciting given BAE's current problems," predicted a businessman with long experience of the region. "They will use political stuff as a point of leverage – whatever tools they have at their disposal."

Precedent is worrying. In 2006 the Saudis threatened to end counter-terrorist cooperation with the UK unless the serious fraud office dropped its investigation into BAE Systems over the al-Yamamah arms deal.

Sir Sherard Cowper-Coles, ambassador to Saudi Arabia at time, assessed that the threat was real and the investigation was shelved on national security grounds. He is now BAE's international business development director.

Unrest in the eastern provinces, home to the country's Shia minority, is another highly sensitive issue, with Gulf officials warning that the Saudis will not countenance interference in their internal affairs.

The Foreign Office categorises the kingdom as a "country of concern" in terms of human rights, but its criticism is discreet. "Saudi Arabia … gets a comparatively easy ride given the scale of the human rights violations in the kingdom," Amnesty International said last week.

Uncertainty over the BP concession suggests pressure is already being applied by the UAE, brooding over regional and local issues. Like the Saudis, the Emiratis were devastated by the west's abandonment of President Hosni Mubarak of Egypt last year and the rise to power of the Muslim Brotherhood across the Middle East. The UAE is also notably hawkish on Iran, whose nuclear programme is at the centre of regional tensions.

Emirati leaders have been angrily expressing their concerns to the UK, diplomats say. Tempers flared recently over coverage of Islamists and human rights issues by the Guardian and BBC, triggering a Twitter campaign accusing Britain of backing "traitors".

Independent observers are pleased that the UK is becoming more critical of the status quo in Bahrain, where the British government criticised a ban on demonstrations as "excessive" last week. "People are surprised that the British are taking such a critical role in assessing the situation in a way that might have a negative impact on trade," said Mansour al-Jamri, editor of the Bahraini newspaper al-Wasat.

But others see more continuity than change in the region as a whole. "The Gulf states are unnerved by the ease with which the US and UK have shifted towards engaging with the Muslim Brotherhood in North Africa," said Jane Kinninmont of Chatham House.

"They don't want what happened to Mubarak to happen to them. Elsewhere in the Middle East things are different, but I struggle to see any difference in policies towards the Gulf. Britain is doing business as usual in Bahrain despite the protests. That's a signal that will not be lost on the Saudis as they deal with unrest in their eastern provinces."

If the Saudis are now silent, their British friends are speaking out. Daniel Kawczynski, the Tory MP who chairs the all-party parliamentary group on Saudi Arabia, says the row over the foreign affairs committee inquiry has been "extremely unhelpful and damaging" to relations between the two countries.

"Every time I take an MP to Saudi Arabia their views are radically changed," Kawczynski said. "There is a huge amount of prejudice in the House of Commons as there is in the country as a whole, because you only ever hear negative press reports. People have a very distorted view of the kingdom. I would be very put out if the Saudis came to this country and challenged and berated me about all our social ills – whether neglect of the elderly or drug abuse or inner city crime. But we constantly criticise the Saudis in a quasi-colonialist and condescending and derogatory manner. You have to consider what would happen if Saudi Arabia was in the hands of an extremist Muslim government."