By Nestor Corrales and Eloisa Lopez

MANILA, May 14 (Reuters) - Gunshots broke out in chaotic scenes at the Philippine Senate on Wednesday where troops had been deployed after a politician wanted by the International Criminal Court urged supporters to mobilise and thwart his imminent arrest.

President Ferdinand Marcos Jr called for calm and said no government personnel were involved in the incident.

There were no immediate reports of casualties.

"We will get to the bottom of this," Marcos said in a video message. "Was this encounter part of destabilisation? We will need to know."

Senator Ronald dela Rosa, a 64-year-old former police chief and the main enforcer of ex-Philippine President Rodrigo Duterte's bloody "war on drugs", had hours earlier urged people to turn out to block his arrest and handover to the ICC.

Marcos said no instruction had been given to apprehend him.

The Hague-based court on Monday unsealed an arrest warrant for dela Rosa, dated November, on charges of crimes against humanity, the same that 81-year-old Duterte is accused of as he awaits trial in the ICC following his transfer last year.

Dela Rosa, who officials said was safe, has denied involvement in any illegal killings in the anti-drugs crackdown during Duterte's 2016-2022 presidency.

'HELP ME', DELA ROSA SAYS

"I am appealing to you, I hope you can help me. Do not allow another Filipino to be brought to The Hague," he said in a video on Facebook from his Senate office, where he has taken refuge since Monday when placed under legislative protection.

Reuters journalists later heard more than a dozen shots ring out at the Senate as those inside scrambled for cover.

Senate Secretary Mark Llandro Mendoza said people he believed to be agents of the justice ministry's National Bureau of Investigation had attempted to enter the Senate and fired shots as they retreated.

But NBI Director Melvin Matibag told GMA News that no agents were there.

The Senate was heavily guarded throughout Wednesday, with security staff wearing flak jackets and carrying rifles and police deployed as protesters gathered, some calling for the arrest of dela Rosa, better known as "Bato", or "rock".

Moments before the gunshots, more than 10 marines in camouflage fatigues carrying assault rifles were seen arriving at the building, a detachment the military said had been requested by the Senate.

Dela Rosa, who returned to the Senate on Monday for the first time since disappearing from public view in November, has appealed to Marcos not to hand him over to the ICC.

The senator has filed an emergency petition with the Supreme Court urging it to block any attempt to transfer him to The Hague. The court on Wednesday gave all parties 72 hours to respond.

DUTERTE'S TOP LIEUTENANT

Dela Rosa was Duterte's top lieutenant overseeing a fierce crackdown during which thousands of alleged drug dealers were slain. Rights groups accused police of systematic murders and cover-ups in a campaign that sought the "neutralisation of illegal drug personalities nationwide".

Police reject the allegations and say the more than 6,000 killed in Project Double Barrel were all armed and had resisted arrest.

Activists say the real death toll may never be known, with users and small-time peddlers gunned down daily in mysterious slumland killings that police blamed on vigilantes and turf wars.

Dela Rosa says he is willing to be tried in a Philippine court and insists any transfer to the ICC would be illegal, as the country is no longer a signatory to the Rome Statute.

The mercurial Duterte, who was elected on promises to kill thousands of drug pushers and criminals, withdrew the Philippines from the ICC in 2018, citing its prosecutor's "baseless, unprecedented and outrageous attacks" after a preliminary examination of the crackdown was launched.

The ICC says crimes committed while a country was a member are under its jurisdiction. The court did not immediately respond to a request for comment on Wednesday's standoff.

Duterte is set to become the first Asian former head of state to go on trial at the ICC, a court he repeatedly dared to pursue him in frequent profanity-laden speeches, during which he said he was ready to "rot in jail" to protect his people from the drugs scourge.

He maintains his innocence.

Posted by: Alma Angeles/NET25 News