WASHINGTON/CAIRO, Jan 21 (Reuters) - The U.S. military said on Wednesday that its forces have transferred 150 Islamic State detainees from Syria to Iraq.

The move comes after the rapid collapse of the Kurdish-led Syrian Democratic Forces in northeast Syria triggered uncertainty over the security of around a dozen prisons and detention camps they had been guarding.

In a statement, the U.S. military said the United States was able to transport 150 Islamic State fighters held at a detention facility in Hasakah, Syria, to a secure location in Iraq.

By Feras Dalatey , Maya Gebeily and Humeyra Pamuk

DAMASCUS, Syria Jan 21 (Reuters) - The Syrian government's rapid takeover of territory long held by the Kurdish-led Syrian Democratic Forces took shape in a string of high-stakes meetings in Damascus, Paris and Iraq earlier this month, nine sources briefed on the closed-door summits told Reuters.

The accounts, not previously reported and shared on condition of anonymity, showed that the U.S. did not stand in the way of an operation that has radically altered Syria's balance of power, at the expense of a one-time ally.

By Menna AlaaElDin and Alexander Cornwell

Jan 21 (Reuters) - U.S. President Donald Trump has invited dozens of world leaders to join his Board of Peace initiative aimed at resolving global conflicts but diplomats say it could harm the work of the United Nations.

While some traditional allies of the U.S. have responded cautiously, and in a few cases have rejected Trump's offer, others including nations that have long had strained ties with Washington such as Belarus have accepted.

WHAT IS TRUMP'S BOARD OF PEACE?

LONDON, Jan 21 (Reuters) - Britain's Prince William will visit Saudi Arabia in February, Kensington Palace said in a statement on Wednesday.

"His Royal Highness' visit comes as the UK and Saudi Arabia celebrate growing trade, energy and investment ties, and as the two nations approach a century of diplomatic relations," the statement said.

The trip, from February 9 to 11, will be his first official visit to Saudi Arabia.

(Reporting by William James; Editing by Catarina Demony)

AMMAN, Jan 21 (Reuters) - The rapid collapse of the Kurdish-led Syrian Democratic Forces in the northeast of the country this week triggered uncertainty over the security of around a dozen prisons and detention camps that they had been guarding, where more than 10,000 Islamic State members and thousands more women and children with ties to the group are being held.

Here is an overview of some of the most important prisons and camps holding IS-linked people in northeast Syria:

HASAKAH PRISONS UNDER SDF CONTROL

DAMASCUS, Jan 21 (Reuters) - Syria's government said a drone strike by the Kurdish-led Syrian Democratic Forces killed seven of its soldiers on Wednesday, though the SDF denied this, in an incident that threatens to derail a ceasefire after days of fighting in the northeast.

The Syrian army called the attack, which it said took place as soldiers were securing a captured military base containing explosives, a dangerous escalation.

Jan 21 (Reuters) - The Syrian government has seized swathes of northern and eastern Syria from Kurdish forces, consolidating President Ahmed al-Sharaa's rule nearly 14 months after Bashar al-Assad was toppled.

The rapid turn of events has brought almost all of Syria back under the authority of the Damascus-based state, following years of conflict that fractured the country, and puts a spotlight on shifting U.S. policy.

WHAT TRIGGERED THE SYRIAN ARMY ADVANCES?

Tensions had been simmering between the government and the Kurdish-led Syrian Democratic Forces for months.

Jan 21 (Reuters) - Rifaat al-Assad, the brother of the late Syrian President Hafez al-Assad known by critics as the "butcher of Hama" for crushing an Islamist uprising in the city in 1982 before unsuccessfully challenging for power and going into exile, died on Tuesday.

He was 88. He died in the United Arab Emirates, two sources with knowledge of his passing said.

President Donald Trump has warned that Iran would be wiped "off the face of this earth" if Tehran ever succeeded in assassinating the US leader.

Arch foes Iran and the United States in recent days have threatened broadscale wars if the leaders of either country are killed.

It came as both nations traded barbs over a protest wave Tehran blames on Washington, after Trump threatened military action if more protesters were killed in a deadly crackdown by Iranian authorities.

Here are the latest developments:

- 'Set their world on fire' -

An Israeli air strike killed an AFP freelancer and two other journalists in Gaza on Wednesday, the territory's civil defence agency said, while the military said it struck "suspects" operating a drone.

Since October 10, a fragile US-sponsored ceasefire in Gaza has largely halted the fighting between Israeli forces and Hamas, but both sides have alleged frequent violations.