Australia will send a warship, a surveillance aircraft and 200 men and women to join a US-led mission to protect oil tankers and ships from attack by Iran in the Straits of Hormuz.

Prime Minister Scott Morrison announced the ‘‘modest’’ contribution to the mission on Wednesday and said the goal was to ‘‘de-escalate’’ tensions in the region.

The international mission is designed to ensure safe passage through the Gulf amid rising tensions between the United States and Iran.

‘‘The government has been concerned with incidents involving shipping in the Straits of Hormuz over the past few months,’’ Mr Morrison said.

‘‘This destabilising behaviour is a threat to Australian interests in the region, particularly our enduring interest in the security of global sea lanes of communication. 15 to 16 per cent of crude oil and 25 to 30 per cent of refined oil destined for Australia transits through the Straits of Hormuz.’’

However Greens leader Richard Di Natale warned the mission would escalate tensions and said it was a mistake to send Australian troops, a surveillance plane and a Navy frigate to help protect shipping lanes from Iran.

“We don’t spill Australian blood on the back of a request from a dangerous administration, led by a dangerous president,” he told ABC’s Radio National on Thursday.

Diplomacy is the best solution for the conflict, the Greens leader believes.

“Instead what we’re going to do is follow the same mistakes that were made so recently in Iraq – following an administration on the basis of a confected lie into a conflict that led to the death of millions of people.”

The decision should have been subject to a parliamentary debate and vote, he added.

Australia’s contribution will include the deployment of a P-8A Poseidon maritime surveillance aircraft to the Middle East for one month before the end of 2019; an Australian Frigate in January 2020 for six months; and ADF personnel to the International Maritime Security Construct headquarters in Bahrain.

Mr Morrison said he will have further discussions about Australia’s contribution with world leaders at the G7.

‘‘Our contribution will be limited in scope and it will be time bound and it will be part of an international mission separate from any other matters in the region,’’ he said.

‘‘Now, this is a modest, meaningful, and time limited contribution that we are seeking to make to this international effort to ensure we maintain free flow of commerce and freedom of navigation which is essential to our security and to our economy,’’ he said.

During the press conference, the Chief of Defence Force Angus Campbell was asked what rules of engagement Australia is operating under and how the Australian warship would respond if a commercial ship for example was seized by Iranian forces.

‘‘Look our people are very well-trained and they’ll be operating under international law and their presence will be to support the security of shipping and freedom of navigation.’’ he said.

Opposition defence spokesman Richard Marles said Labor supported the decision.

‘‘We do so on the basis of this being a mission, which is tightly framed around freedom of navigation for commercial shipping within the Straits of Hormuz and the Persian Gulf. Freedom of navigation for Australia as a trading island nation, is completely central to our national interest,’’ he said.

‘‘I’d like to note that this morning the Prime Minister spoke with the Leader of the Opposition, as the Minister Defence also spoke with me to outline exactly Australia’s commitment in relation to this mission. We thank them for those calls.’’

However, Centre Alliance Senator Rex Patrick warned the mission was ‘‘risky’’.

‘‘Prime Minister Scott Morrison’s decision to commit Australian air and naval forces to support a United States commanded effort to police sea lanes in the Straits of Hormuz could, without little or no notice, draw Australia into a broader conflict between the United States and the Iran,’’ he said.

‘‘Australia already has some 800 personnel deployed in the Middle East region. This new commitment of another 200 personnel, in an operation specifically focussed on Iran, will further deepen Australia’s military involvement while President Trump calls the shots.’’