Foreign military vessels responding to a request for assistance from the Solomon Islands government would also be exempt, Prime Minister Manesseh Sogavare said.

The Solomon Islands signed a security pact with China in April, which a leaked draft said allows the Chinese navy to replenish in Honiara, prompting concern from the United States, Australia and New Zealand about China's growing influence. 

Last week, Sogavare announced a moratorium on foreign navy vessels entering port following incidents in which a US coast guard vessel and a British navy vessel on patrol for illegal fishing were unable to refuel in Honiara. 

Questioned by opposition members of parliament about the moratorium, Sogavare said military vessels deployed under the auspices of the Solomon Islands International Assistance Force (SIIAF), a treaty under which Australia, New Zealand and Fiji work with the Solomon Islands police, would be exempt.

"Military vessels deployed under SIIAF are therefore exempted during the period of the moratorium," he said.

The United States, which plans to open an embassy in Honiara, said it was informed on Aug. 29 of a moratorium on all foreign navy vessels. 

A month earlier, the United States pledged to boost aid and increase illegal fishing surveillance in the Pacific in an attempt to counter China's growing presence.

The cabinet had decided to impose the moratorium on military vessels as it reviewed "the benefits and risks to Solomon Islands of any visits by any military vessels", Sogavare said, though adding the moratorium was not aimed at the United States.

"We are not targeting the United States of America," he said.

The United States, Australia, New Zealand and Britain had become involved in the illegal fishing patrols and his office needed to know more about the vessels arriving, he said.

The Forum Fisheries Agency, which is based in Honiara and represents Pacific Island nations with rich tuna stocks, would need to notify his office about which naval vessels are taking part in surveillance patrols to gain an exemption, he said.

"We don't know who the hell is coming," he added. 

Minister for Foreign Affairs Jeremiah Manele said a report on the matter was expected at the end of next week.

Tensions are high in Solomon Islands as changes to the constitution to delay a general election are expected to pass parliament this week. 

Australia advised in a travel warning on Saturday of the risk of civil unrest as the parliament considers "significant legislation"