A Donald Trump presidency could adversely affect world economy, increase the potential of Islamic terror attacks and lead to a U.S. trade war with Mexico and China, a British research organisation has warned.

The Economist Intelligence Unit (EIU) released its updated global risk assessment, ranking the election of Trump a 12 on a scale of one to 25 — the same number it assigned to the possibility that jihadi terrorism would destabilise the global economy, NBC News reported.

Making a similar warning, the Washington Post on Wednesday called for the Republican Party to aim for as brokered convention to prevent a Trump nomination and possible presidency, pointing out that Trump "presents a threat to American democracy."

"Mr. Trump resembles other strongmen throughout history who have achieved power by manipulating democratic processes," the paper's editorial board wrote. "Their playbook includes a casual embrace of violence; a willingness to wield government powers against personal enemies; contempt for a free press; demonization of anyone who is not white and Christian; intimations of dark conspiracies; and the propagation of sweeping, ugly lies."

The EIU based its assessment on Trump's hostility toward free trade, his accusing China of being a currency manipulator, his advocacy of a harsher response to terrorism—including the killing of terrorists' families—and his proposal to send U.S. ground troops to Syria to fight the Islamic State (ISIS) and take its oil.

This appeared to be the first time that the EIU had rated a presidential candidate's election as a global risk, according to Politico.

"His militaristic tendencies towards the Middle East (and ban on all Muslim travel to the U.S.) would be a potent recruitment tool for jihadi groups, increasing their threat both within the region and beyond," the EIU report said.

The group said it also expects that a President Trump will face stiff opposition in Congress, both from Democrats and Republicans.

This "internal bickering" could in turn weaken America's leadership in the world, the group said.

Aside from a Trump presidency, the EIU listed the following as global threats: a sharp economic slowdown in China, a collapse of investment in the oil sector, the breakup of the European Union, the further rise of jihadi terrorism, and Russian actions in Ukraine and Syria leading to "a new cold war."