US President Donald Trump says he has "inspected" the Reflecting Pool in Washington DC, and that "work will begin immediately" to repair the American landmark.

Despite a recent multi-million dollar renovation, including a fresh coat of blue paint, the historic structure continues to face issues - most prominently algae turning the water a bright shade of green.

The pool may need to be drained and refilled for a second time this month, according to Trump, who flew over the site in a helicopter on Sunday while on his way back from Camp David.

It comes as Trump claims the pool's paint has been marred by vandals ahead of the 250th anniversary of the country's 4 July independence day.

US Attorney for Washington DC Jeanine Pirro has vowed to aggressively prosecute anyone found to have damaged the pool.

"Anyone who is in a position of vandalising or attempting to vandalise will face the criminal justice system in DC," she told Fox News on Sunday.

According to a senior Trump administration official, five people have been arrested for vandalism and five more were issued with citations by police on Saturday night.

A total of 14 police reports have been filed, the official told CBS, the BBC's US partner, including one person who Trump claimed had used a blade "put a 250 foot long gash into the beautiful facade".

US Park Police, the federal police agency which patrol the monuments on the National Mall, did not reply to a BBC email requesting confirmation of the arrest figures.

The Reflecting Pool, built in the 1920s and stretching 2,030ft (619m) between the Lincoln Memorial and the Washington Monument, has long been beset by leaks, structural deterioration, faulty pipes, algae growth and bird droppings.

But despite the makeover, which cost an estimated $13m (£9.8m), the pool has continued to be plagued by algae and more recently paint problems, which have seen media and park visitors document pieces of the new paint job peeling from the bottom of the pool.

On Sunday, Trump took to Truth Social to announce that "work will begin immediately on fixing the seriously vandalized Reflecting Pool".

"I just inspected it, and could only say to myself, and those gathered around me, WOW, who would do such a thing? SICK, DERANGED PEOPLE!"

According to reporters travelling with Trump, his online post came as his helicopter was approaching the White House on return from the presidential retreat at Camp David in Maryland, where he spent the weekend.

He did not visit the pool via ground transportation, and appears to have inspected it from the air.

Champion canoeist David "Davey" Hearn told the BBC that he did not do anything wrong, and was simply touching the peeling paint.

Hearn told BBC News on Saturday that he "didn't destroy, rip, tear, peel, or remove any part" of the paint.

"The condition of any part of the reflecting pool didn't change," he insisted.

"It wasn't affected. It was the same before I got there as when I walked away from it."

He called his arrest an "arbitrary, capricious prosecution".

Officials have been using chemicals, including reportedly hydrogen peroxide, to clean a green algae bloom which has taken hold in the pool since it was re-filled following a paint job earlier this month.

Over the weekend, a news photographer spotted a dead duckling floating in the pool. It is unclear how the animal died or whether it was harmed by work being done on the Reflecting Pool.

Rosalina Stancheva Christova, a professor of aquatic ecology who studies algae at George Mason University, took a sample of the water from the pool on 16 June, and confirmed that the green algae inside is a species called Desmodesmus, which is "absolutely harmless" to people or animals.

However, there is a concern that a bird visiting the pool could introduce other forms of algae which can carry harmful bacteria.

"These ecosystems are very dynamic, and the algal composition is changing really quickly," she says, adding that the pool should be monitored constantly "to know which organisms are living there".