Saudi Arabia has boosted its lobbying efforts in the UK recently, sparking concerns that Riyadh is exchanging hospitality for MPs' silence on human rights abuses in Yemen.
Conservative MPs have accepted more than £130,000 in gifts from the Saudi government since the start of the Yemen war in 2015, according to the Register of Members' Financial Interests.
This year alone 13 Conservative MPs and one Labour MP have received a total of £94,189 in hospitality from the Saudi regime, including business-class flights, luxury accommodation and food.
One Conservative MP, Leo Docherty, who led a six-day delegation of four backbenchers to Riyadh in September, faces a probe by the parliamentary standards commissioner after he failed to disclose the trip.
Tom Brake, an MP for the Liberal Democrats, wrote a letter of complaint and demanded Docherty's trip is investigated.
"It's bad enough seeing the government's constant failure to condemn Saudi Arabia's appalling human rights record, but now we're seeing a growing band of Tory MPs enjoying free trips courtesy of the Saudi regime," he told Middle East Eye.
"The job of an MP is to scrutinise the government and their relationship with foreign regimes. Being best buddies with those same regimes is hardly likely to lead to forensic scrutiny of the UK government's actions."
In September, the UK government was accused of blocking a UN probe into human rights abuses committed in Yemen. The revelation emerged after Saudi Arabia threatened its allies with economic retaliation if they decided to support the resolution.
Last week, the UK's former international development secretary, Andrew Mitchell, accused the UK of being "dangerously complicit" in Saudi Arabia's foreign policy towards Yemen which is "directly promoting a famine and the collective punishment of an entire population."
UK arms sales to Saudi Arabia have surged by almost 500% since the start of its bloody conflict with Yemen.
Sophie Baggott, Policy and Research Associate at the Bahrain Institute for Rights and Democracy (BIRD), also condemned the UK MPs for accepting hospitality from Riyadh while it wages war against Yemen.
She told IBTimes UK: "Accepting gifts and cosying up to corrupt regimes is a dismal failure of MPs' responsibilities to scrutinise the UK Government's foreign policy. The MPs receiving gifts risk turning into puppets whitewashing the Saudi regime."
She called on the Parliamentary Commissioner for Standards to ensure that the hospitality gifts are not in breach of conduct.
"The Saudi-led coalition's bombardment of Yemen has induced the world's worst man-made humanitarian crisis, which has gone hand in hand with a surge in the UK's arms sales to Saudi Arabia. While the UN has blacklisted this coalition for killing and maiming children in Yemen, some of our politicians are busy legitimising the Saudi regime through free trips," Baggott said.