Addressing the GCCs annual summit in the Bahraini capital Manama on Wednesday, May said Britain planned to invest more than $3.7 billion in the region over the next decade.
As part of the renewed relationship that I want to forge with you, the United Kingdom will make a more permanent and more enduring commitment to the long-term security of the [Persian] Gulf, she told leaders of Saudi Arabia, Kuwait, the United Arab Emirates, Qatar, Bahrain and Oman.
"Gulf security is our security," she said. "In challenging times you turn to your oldest and most dependable friends."
Before departing London for the two-day visit, May said she wanted to lay the foundations for a new chapter in ties with Persian Gulf countries as the UK was leaving the European Union.
The prime minister also spoke about discussions to boost trade with the Persian Gulf countries, which are important markets for UK arms sales.
"I want these talks to pave the way for an ambitious trade arrangement" after Brexit, she said.
[caption id="" align="aligncenter" width="555"]
British Prime Minister Theresa May (C) poses with Persian Gulf Cooperation Council leaders for a group picture on December 7, 2016. (Photo by AFP)[/caption]Rights groups had called on May to cancel her trip to Bahrain, criticizing her for putting military ties and commerce ahead of human rights.
Scores of people have been killed and hundreds of others injured or arrested in the Bahraini crackdown on the anti-regime activists, who have been holding protests on an almost daily basis since February 2011. The protesters demand the Al Khalifah dynasty relinquish power.
In her televised address, May also touched upon issues such as the Iran nuclear agreement, the ongoing conflicts in Yemen and Syria as well as the military campaign against the Daesh terrorist group.
The prime minister said the 2015 nuclear deal with Iran was vitally important for regional security.
Her comments were in contrast with those of US President-elect Donald Trump, who said during his campaign that he would rip up the deal or renegotiate its terms.
May, however, said the UK and its allies must work together to counter what she called Irans aggressive regional actions.
The UK will open a massive permanent military base in Bahrain and deploy warships in the Persian Gulf.
The base, which is the first such facility being opened by Britain in the Persian Gulf region in four decades, will be launched next month.
Britain will station around 600 military forces at the Royal Navy Facility and will deploy its warships to patrol the surrounding waters and guard oil and gas shipments in the waters.
