Philippine President Rodrigo Duterte on Friday warmly thanked Russian leader Vladimir Putin for shipping weapons to his struggling military, adding that he will buy more Russian arms in the future.

"I want to pass on words of thanks from the Philippine people for the timely aid that Russia provided by giving us trucks and weapons," he said as the two met on the sidelines of the APEC summit in Danang, Vietnam.

Duterte said the military "was delighted at the weapons" in remarks translated into Russian.

Last month Russia handed over army trucks and thousands of Kalashnikov assault rifles to Duterte during a visit by Russian Defence Minister Sergei Shoigu, a first-ever visit by a Russian defence minister to the US ally.

The weapons shipment is also believed to be the first ever from Russia to the Philippines.

The Philippine military in October declared an end to a five-month battle in the southern city of Marawi where the poorly-equipped army struggled to oust militants loyal to the Islamic State group. 

"These are high-precision weapons. We had to lead a new type of warfare, we had to fight snipers... we were fighting back house-by-house. That's not so easy," Duterte told Putin.

He said he initially intended to buy weapons in the US but "the United States has equal authority of Congress and President, so it was not so simple."

Duterte last year threatened to sever defence ties with the United States following criticism from the administration of former US leader Barack Obama over his crackdown on drugs, which has seen police kill thousands of people.

However relations warmed under the presidency of Donald Trump.

"The weapons we received from Russia, modern weapons, were given to special police regiments. That was very important. I intend to continue buying these weapons in the future."

In a reserved response, Putin said that "weapons are important" but Duterte's "readiness... to fight the threat of terrorism" is even more significant.

"We are ready to develop our relations, including in the military sphere," he said.