Manila, Philippines - A homemade bomb detonated near the entrance of the Philippine's justice ministry early on Monday, officials said, hours before President Ferdinand Marcos was due to give a major address.

The explosion came just after midnight, and resulted in no casualties. A second, unexploded device was found hours later near the Philippines' Senate, shortly before Philippine President Ferdinand Marcos was due to give his annual State of the Nation address.

National police chief Jose Melencio Nartatez Jr told reporters on Monday there was a "big possibility or probability that the two (incidents) are related."

He said that, while police had contingency plans for "bomb threats, actual bombings, and other [things]… something got past us and exploded in front of the Department of Justice."

Environment and Climate Whales and dolphins to meet devastating fate due to severe marine heatwave, experts warn

It was not immediately clear how large the early morning blast had been.

"We are still investigating, so we cannot give you details on how massive or small the explosion was," Manila police spokesman Philipp Ines told AFP.

Images posted by Philippine media showed what appeared to be a vehicle windshield cracked by the blast and a small amount of debris scattered about.

Police said in one report the device at the Senate had been spotted on a street abutting the building just before 8:30AM by a tow truck driver, who alerted security staff.

Personnel trained in handling explosive ordnance removed material from the scene that included a blasting cap, clock, and a jar containing a "brown powder" for testing.

The bombing comes less than a week after Manila hosted a summit of the Association of Southeast Asian Nations, including Secretary of State Marco Rubio.

Marcos's speech on Monday marks a time of heightened political tensions in the country, and increasing tensions and clashes with China.