Ken Isaacs, who is United States (US) President Donald Trump's controversial nominee to lead the United Nations (UN) migration agency, dismissed allegations of anti-Muslim bias on Thursday, telling AFP he “never” considers the faith of those in need.

But Isaacs, also accused of being a climate science sceptic, did not directly confirm that he recognises climate change as a key driver of global migration, something the International Organization for Migration (IOM) has identified as a key component of its mission.

Isaacs has taken a leave of absence from his post as vice president of the Christian charity Samaritan's Purse since being tapped by Trump on February 1 to take over the Geneva-based IOM.

Isaacs also held a senior role with the US Agency for International Development during George W. Bush's administration.

Following his nomination for IOM director-general — a job traditionally held by an American — The Washington Post highlighted a series of anti-Muslim social media posts on Isaacs' accounts, which have since been removed.

The paper reported a series of tweets between 2015 and 2017, in which Isaacs claimed the Quran “instructs” Muslims to commit acts of violence, suggested Syrian Christian refugees should be prioritised over Muslim ones and challenged claims that Islam was a peaceful religion.

In a February 11 editorial, The Washington Post said his leadership of IOM “would be an embarrassment to the United States” while multiple civil society groups have voiced concern over the nomination.

Isaacs has previously expressed “regret” for his “careless” comments, and the State Department said it was “proper” for him to apologise.

But in written responses to questions submitted by AFP, Isaacs sought to further defend his more than three-decade record as a humanitarian worker in major trouble spots like Somalia, South Sudan and Afghanistan.

“As a person of faith, I have deep respect for people of all faiths, including followers of Islam,” Isaacs said in an email sent by a spokesman.

“I have dedicated my life to serving fellow human beings on the run from wars, famines, and the most incomprehensible disasters known to man. I have never paused to consider their faith, and I never will,” he added.

Man-made climate change?

IOM's 169 member states will elect a new director-general in June to replace veteran US diplomat William Lacy Swing.

Isaacs currently faces two rival nominees from Costa Rica and Portugal, including a sitting deputy IOM chief, but the director-general post has been held by an American throughout the organisation's 67-year history, with one exception in the 1960s.

Isaacs' critics have also zeroed-in on a Facebook post in which he called the link between national security and climate change a “joke”, specifically regarding the 2015 Paris climate accord.

Asked by AFP if he recognised man-made climate change as a key driver of global migration — which IOM does — Isaacs said: “I have witnessed with my own eyes how weather patterns, drought, low crop yield, desertification, hurricanes, typhoons and extreme weather trigger migration.

"IOM's comprehensive approach takes all of these factors into account, and I see every reason to uphold its central objectives in managing environmental migration”, he added, without using the words “climate change” in his three-paragraph answer.