Honiara said the vessels had not sought access in time, and this prompted a review of the arrival procedure.

But the move marks a departure from routine and has raised concerns about China's influence.

Honiara signed a security pact with Beijing in April, sparking alarm among US allies and other Pacific islands.

On Tuesday, Prime Minister Manasseh Sogavare issued a statement clarifying "misinformation" in media reports on the US and UK boats.

He said both ships — the US Coast Guard Cutter (USGC) Oliver Henry and the HMS Spey — had failed to be granted approvals in time because of a delay in paperwork.

"The delay in these approvals demonstrates the need for the government to review and refine its approval requirements and procedures for visiting military vessels to Solomon Island," Sogavare said.

"The government has asked all partner countries with plans to conduct naval visits or patrols to put them on hold until a revised national mechanism is in place."

He said this "universally" applied to all visiting foreign naval vessels.

US embassies told the BBC they had received notice of the Solomon's policy update on Monday.

"The United States received formal notification from the Government of Solomon Islands regarding a moratorium on all naval visits, pending updates in protocol procedures," an embassy statement read.

This came after Solomon authorities failed to provide diplomatic clearance to the USCGC Oliver Henry, which was making a routine stop in Honiara on 23 August, forcing the ship to divert to Papua New Guinea.

However it said one of its hospital ships, the US Navy Ship Mercy, had been granted entry into the Solomons' waters on Monday for a separate operation- although that ship was granted approval before the announced moratorium.

British ship HMS Spey was also forced to turn away from Honiara after it failed to get approval from Solomon authorities in time. It is one of Britain two ships based permanently in the Pacific region.

It's unknown if any Chinese vessels have been affected so far.

The US has sought to strengthen its relations with all Pacific island nations since the Solomons leader made the unexpected announcement in April that his government had secured China as a major security partner.

This led to fears that a Chinese military base could potentially be set up on the island — though this has been strongly denied by Sogavare.

In the face of China's advances, Australia's newly elected center-left government launched a series of visits in May to several Pacific Island nations, to reinforce its relationships with its neighbors.

The US has also been making efforts to engage. In February, it re-opened its embassy on the island after a 29-year absence.