Theresa May's trade push in the Middle East has been branded the "shabby face" of Brexit by critics.
As the Prime Minister used a two-day visit to Bahrain to line up business opportunities, critics accused her of ignoring the Gulf state's much criticised human rights record.
Liberal Democrat foreign affairs spokesman Tom Brake said: "So this is the shabby face of Conservative Brexit politics: the Prime Minister travelling the world desperately trying to stitch up new trade alliances with anyone who will deal, in this case Bahrain, where peaceful dissenters are jailed and even tortured.
"Meanwhile foreign workers face passport confiscation, physical abuse and forced labour. Is this what Brexit means, Prime Minister?"
Mrs May insisted human rights were on her agenda as she jetted into Bahrain to attend the summit of the Gulf Co-operation Council (GCC).
"Whenever we have concerns about human rights issues we do raise those in the discussions that we have.
"Obviously, as I'm coming out here to have a meeting with all the six GCC states, we will be talking about a range of issues.
"The only way in which you can actually raise issues around human rights, and have a meaningful discussion with them about it, is by engaging with them, rather than trying to step back and stand somehow on the outside. It's important to have that engagement."
Mrs May is using her visit to strengthen aviation security by improving passenger screening systems and information sharing to try to bolster detection of suspects.
The Prime Minister is announcing a new working group with regional nations to combat the financing of terrorists. The UK is to provide three specialist cyber experts to the Gulf states to help deal with extremism.
With Britain spending £3 billion on defence projects in the Gulf region over the next 10 years, Mrs May is announcing a new strategic partnership to deal with crisis response.
The Prime Minister is visiting the Royal Navy's flagship HMS Ocean on Tuesday to address the 900 personnel on board.
Downing Street stressed that close security relations with the Gulf states have already produced benefits, such as in 2010 when a "printer bomb" was discovered at East Midlands Airport as a result of information received from Saudi Arabia.
Mrs May is also announcing a new permanent British defence staff in Dubai to co-ordinate regional activities, and a dedicated military officer embedded with Bahrain's Ministry of Interior bomb disposal unit to provide management support and training.
The Prime Minister said: "Now more than ever, Gulf security is our security. That's why we are investing in hard power there, with over £3 billion of defence over the next decade - spending more in the Gulf than in any other region of the world.
"And it's not just about military power, we also need to work together to respond to new and diversifying threats. So, on my visit here, we are agreeing new co-operation to do more to prevent radicalisation and to tackle terrorism."
Mrs May will attend a dinner with the leaders of Saudi Arabia, Kuwait, the United Arab Emirates, Qatar, Bahrain and Oman on Tuesday, before addressing the plenary session of the summit on Wednesday.