It is the 4,000-kilometre cable that Canberra did not want Beijing to build.

But today, Australian and Solomon Islands officials will sign up to the first stage of a multi-million-dollar contract to sink an undersea high speed internet link between the impoverished Pacific nation and the Australian mainland.

Getting to this stage has taken diplomatic pressure and rare intervention from one of Australia's top spies.

Australian intelligence agencies never wanted the Solomon Islands to allow Chinese company Huawei to build the link, and were keen to prevent it happening.

And the backdrop for today's signing is especially acute, given Federal Parliament is soon to debate foreign interference laws curbing the influence of overseas powers.

The original cable contract struck between Solomons and Huawei has been viewed as a prime example of Beijing seeking to flex "soft diplomacy" in the Pacific.

Australia is intent on using its own political muscle in the Pacific region in response.

Solomon Islands Prime Minister Rick Houenipwela is currently visiting Australia, and has met with Prime Minister Malcolm Turnbull in Canberra for the two countries to sign off on where the cable will land in the Solomons.

Eighteen months ago, it was very different.

The Solomons Government had inked a deal with Huawei in late 2016 to consider constructing the cable, in a bid to improve the nation's often unreliable internet and phone services.

But the Department of Foreign Affairs and Trade (DFAT) confirmed this year it would step in and foot most of the bill — effectively forcing Huawei from the project.

Senior officials, including spy boss Nick Warner, were visiting the Solomon Islands in July 2017 as Australia's 14-year peacekeeping mission wrapped up.

Concerned about Huawei being permitted to plug into Australia's telecommunications infrastructure, they told the local government that Canberra was unlikely to grant the company a so-called "landing point" for the cable on the Australian mainland.

They believe that while Huawei is an independent company, it retains links to the Chinese government and could pose a threat to Australian infrastructure in the future.

It was at that time Australian officials offered to step in, with a deal that's been described to the ABC as "very generous" and almost halving the cost of the project for the Solomon Islands Government.

Australia already has a number of underwater cables connected around the region. ( Supplied: TeleGeography )

DFAT is now funding about two thirds of the cost of the cable to the Solomons and to neighbour Papua New Guinea, and a $2 million scoping study by Sydney company Vocus has been completed.

Money has been allocated in the Budget, but is being kept under wraps before the project is put out to tender. However, it is believed it could cost the aid budget more than $100 million.

Government sources have told the ABC that Australia's Pacific neighbours should not be left in a position where they only have China to turn to for infrastructure investment.

Australian concerns over Huawei are not new. It was blocked from being allowed to work on the construction of Australia's National Broadband Network (NBN), and there are new concerns about its potential involvement in the development of the nation's 5G mobile network.

Solomons PM not publicly outlining security concerns

Mr Houenipwela became Solomon Islands leader after the contract negotiations, and was highly critical of the process.

He was grilled on what pressure Australian officials had put on his government while in New Zealand last week.

"We have had some concerns raised with us by Australia, and I guess that was the trigger for us to change from Huawei to now the arrangements we are now working with Australia on," Mr Houenipwela said.

Sorry, this video has expired Solomon Islands PM says Australian authorities made their concerns about Huawei clear

But he would not be drawn on security issues this morning in Canberra, simply saying his nation chose Australia because it offered the best deal.

"Looking at the two projects, from our perspective this is the best one," he said

"The cost is much, much less for us. Australia is paying two thirds of the cost."

Mr Houenipwela added that the cable would make it easier to conduct business in the Solomons, while his Ministers said it would transform schools in the Pacific nation by connecting them to the outside world.

Foreign Minister Julie Bishop also would not say what security concerns Australia raised with the Solomon Islands about the project.

"We believe the alternative we offered is cheaper, faster and more reliable than that offered by the competitor," Ms Bishop said.

"We want the Solomon Islands and other countries in the Pacific to have alternatives, to have options, and Australia is well placed to offer that."

Ms Bishop shrugged off suggestions that Beijing might be irritated that Australia had scuppered Huawei's bid for the project.

"It's a competitive world — we put forward an alternative and the Solomon Islands are accepting it," she said.

Australia offered a new sweetener this morning, announcing it would also help fund a domestic internet cable in the Solomons.

Prime Minister Malcolm Turnbull said the project would amplify the benefits of the undersea cable by connecting remote provinces with the capital, Honiara.

Malcolm Turnbull met with Solomon Islands Prime Minister Rick Houenipwela to discuss the details. ( ABC News: Luke Stephenson )

DFAT officials have defended Canberra's involvement in the project, and argued they had been talking to our Pacific neighbours for some time.

"Both the Solomon Islands Government and the Papua New Guinea Government have been exploring for some time a range of different options in terms of financing a cable," the department's Pacific division's Daniel Sloper told Senate Estimates last month.

"In discussion with us, we looked at options that could deliver that as fast as we could and with a reliable and sound technology.

"There was an agreement between the governments that we could provide that in the time period they were looking for."

He said the Chinese telco had not approached the Federal Government to connect into the Australian network by the time Canberra stepped in.

"In terms of Huawei, the company you mentioned, at no point did that company or, in fact, the Solomon Islands' responsible telecommunication authority that would be submitting applications, put forward an application to Australia."