Papua New Guinea Prime Minister James Marape says the US has been a "silent" security partner to his nation but a defence co-operation pact to be signed when Joe Biden arrives will see Washington "stepping out".

Biden will be the first sitting US president to visit Papua New Guinea, and Marape confirmed on Tuesday that two security agreements will be signed, on defence co-operation and maritime surveillance.

"These signings will add value to our domestic security, as well as strengthen our own military, our police, our navy," he told radio station 100FM.

The government would provide details on the agreements on Thursday, he said.

"The USA has been a strong security partner of us, but silent, almost deep at the back. Now for the first time now they are stepping out, coming to the front, engaging with PNG like never before," Marape added.

Washington is seeking to nudge Pacific island nations away from security ties with China, after Beijing last year struck a security pact with the Solomon Islands, and as tensions rise over Taiwan. PNG sits near crucial sea routes between Australia, Japan and the United States.

"At the moment in our waters, especially in our 200km waters, we have illegal fishing, we have illegal transportation, we have drug cartels ... we want to ensure our country is secure from illegal activities," Marape said.

PNG's former foreign minister Justin Tkachenko told Reuters last week an agreement to allow the US Coast Guard to patrol PNG's vast exclusive economic zone would also give PNG access to US satellite surveillance.

Tkachenko resigned on Friday after public backlash sparked when his daughter posted TikTok videos about her luxury travel to the coronation of King Charles in London.

Marape has taken over the foreign minister's role as PNG prepares for the arrival of Biden, US Secretary of State Antony Blinken, and Indian Prime Minister Narendra Modi on Monday.

Marape said it was a "big moment" for his nation.

Modi will meet with Pacific island leaders from 18 countries on Monday morning. Biden will stop for three hours on Monday evening, before travelling to a summit of the Quad countries - the United States, Japan, India and Australia - in Sydney.

China has sought closer trade and economic ties with PNG, and last year failed to strike a security and trade pact with 10 Pacific island nations.