“I'm very afraid, will there be more wars? Will America attack Muslim countries again?” asked Indonesian activist Alijah Diete, as Muslims reeled Wednesday from Donald Trump's shock US presidential election victory.

After a bitter campaign in which fiery anti-Muslim rhetoric was central to Trump's populist strategy, many followers of Islam were dumbfounded that Americans had chosen him to lead the world's greatest power.

With markets in a tailspin and the world looking on in shock, there was growing anxiety in Pakistan, Indonesia and Bangladesh ─ home to more than a third of the world's 1.5 billion Muslims ─ about what his dramatic election win would mean for the Muslim world.

Worried followers of the faith listed a litany of problems for Muslims they believed would come with a Trump presidency ─ from the billionaire following through on a pledge to ban Muslims from entering the US, to a potential surge in militancy driven by tougher American policies.

A senior Pakistani government official, speaking anonymously, called the news "absolutely atrocious and horrifying" while others in the country also lamented the results.

"I am disappointed to see Donald Trump winning because Hillary Clinton is a good woman, she is good for Pakistan and Muslims all over the world," said Ishaq Khan, 32, speaking at an Islamabad market.

"She was talking about world peace ─ but Trump was talking about fighting against Muslims."

“Americans have just screwed the world yet again,” said Syed Tashfin Chowdhury, a Bangladeshi who has several close friends in the US.

Thousands in the country watched in shock as the results rolled in and Facebook lit up with horrified reactions.

“I'm in disbelief,” said the Indonesian Muslim activist Diete, 47. “I thought Americans are supposed to be intelligent and mature. How is it possible Donald Trump won?”

Trump appealed to America's disillusioned white majority with populist pledges to tear up free trade deals and deport illegal immigrants, but it was his attacks on Islam that sparked some of the greatest anger abroad and drew accusations of xenophobia and racism.

He made his most controversial remarks last December, shocking the Islamic world by calling for a “total and complete shutdown” of Muslims entering America after an apparently radicalised Muslim couple carried out a mass shooting in California.

'Muslims are foreigners to him'

Following his improbable election victory Wednesday, anger and anxiety were again high among Asia's Muslims.

In Indonesia, the world's most populous Muslim-majority country, there was a mixture of shock and nervousness about how the victory would affect the relationship with traditional ally the US, as well as future relations between America and the Muslim world.

"I am very concerned that the relationship between the US and Muslim countries will become tense again," said Diete, while law firm employee Nikken Suardini said the proposal to bar Muslims from the US was "just not fair".

In a country that has long struggled with militancy and seen hundreds head to the Middle East to fight for the militant Islamic State (IS) group, fears were also mounting that anti-Islamic policies under Trump could be seized on by extremists to bolster their cause.

"When the United States uses hard power, extremists gain a momentum," said Zuhairi Misrawi, an Islamic scholar from moderate Indonesian Islamic organisation Nahdlatul Ulama.

"Those who will be the happiest when Trump wins are ISIS," he said, referring to IS by another name. The militant group is struggling to hold onto its territory in Iraq and Syria in the face of a fierce military onslaught.

Some observers were hopeful that the 70-year-old Republican maverick's rhetoric was aimed at winning votes and would not be translated into tough xenophobic policies.

"We hope that Trump's remarks against Muslims were only to boost his campaign," said the Council of Islamic Ideology's Maulana Tahir Ashrafi.

For others, a major concern was the potential effect of a Trump presidency on the millions of Muslims living in America.

"In Donald Trump's view, Muslims are not part of America," said Munarman, a spokesman for Indonesian hardline group the Islamic Defenders' Front, who goes by one name. "Muslims are foreigners to him."