The actions of Witness K and Bernard Collaery were a valued part of the “collective effort” that led to the historic maritime boundary treaty between Australia and Timor-Leste, the Timorese foreign minister has said.

In an exclusive interview with Guardian Australia, the foreign minister of Timor-Leste, Dionísio Babo Soares, said the two nations were at a new stage of their relationship after the historic signing of a maritime boundary treaty, but Timor-Leste was not forgetting the past.

The treaty, signed at the United Nations in March, followed decades of fractious negotiations about the boundary, which would determine lucrative oil and gas rights, and a lengthy conciliation process under the United Nations Convention on the Law of the Sea (Unclos).

In one of the most significant episodes of the negotiation process, Australia was revealed to have bugged the offices of Timorese negotiators during critical talks.

A former employee of the Australian Secret Intelligence Service known only as Witness K, and his lawyer, Collaery, are being prosecuted for their role in the revelations, which has drawn condemnation from members of Australian parliament, human rights and legal groups, and the former Timor-Leste president, Jose Ramos Horta.

Asked if the maritime border treaty could have been reached without the intervention of Witness K and Collaery, Babo Soares said there were many contributing factors.

“First of all is, of course, the political will. Second is the acting in good faith – not only by politicians but also the people of Australia at large,” he said.

“We’ve seen a lot of support from the civil society in Australia – the Timor Justice Campaign, we’ve seen also the support of the veterans of Australia who think the ‘fair go’ should be negotiated through Unclos.”

“But we also value very much the intervention of the individuals that you have touched on, and this is all part of concerted efforts that have contributed.”

In a historic visit to Timor-Leste last month Australia’s foreign minister, Julie Bishop, said the prosecution was a domestic law enforcement matter for Australia.

Babo Soares said the Timor-Leste government respected Bishop’s statement and the sovereignty of Australia, but his government would be following the issue closely.

“As this actually falls under the jurisdiction of Australia we will respect the laws of the country,” he said. “This is a matter for Australia to resolve.”

However he said Timorese people and civil society groups were free to express their dissatisfaction with the prosecution and many had done so.

Australia’s tactics in seeking a greater share of the Greater Sunrise fields have repeatedly drawn criticism, most recently after newly declassified government documents revealed it was a driving factor in Australia’s early recognition of Indonesia’s invasion in the 1970s.

Babo Soares said Bishop’s visit marked “a new chapter for the relationship”, and Timor-Leste intended to “look ahead”.

“It doesn’t necessarily mean that we are forgetting the past or burying the past, but we are using it as a reference to actually improve our future relations.”

The two governments released a joint communique following the July ministerial visit pledging, among other things, to strengthen security and defence partnerships and to deepen collaboration on maritime security.

Babo Soares said the collaboration would involve Timor-Leste working with Australian defence and customs agencies in response to transnational crime such as drug smuggling, and protecting assets in the Timor Sea – including the Greater Sunrise oil and gas fields when they are developed.

The maritime boundary treaty mostly determined the split of resources between the two countries, but a difference of 10% depends on whether the resources will be piped to Darwin or Timor-Leste for processing.

Timor-Leste is insisting processing must take place there, but operators of the joint development, including ConocoPhillips and Woodside, have opposed the suggestion.

Timor-Leste is the second most resource-dependent nation on earth, but the reserves currently accessed are predicted to run dry by 2022-23. Babo Soares dismissed concerns and suggested printed reports about the state of the Bayu-Undan fields were exaggerated.

He pointed to economic diversification projects funded by the government, to reduce reliance on oil and gas.

Regardless, the extraordinarily long time it has taken to determine rights over Greater Sunrise mean it is essentially impossible it could be developed in time for the revenue to replace that of Bayu-Undan.