The federal environment department says it is not aware of any countries other than Australia planning to use controversial “carryover credits” to meet international climate commitments.

The comment, at a Senate estimates hearing on Monday, comes as the Morrison government rebuffs calls from international leaders, analysts and activists for it to abandon the use the credits to meet its 2030 Paris emissions goal.

The government says it has earned the right to use the credits, which represent the amount of carbon dioxide by which Australia has “beaten” the targets set under the previous international climate agreement, the Kyoto protocol.

Critics say the credits do not represent the emissions reductions needed to help meet the Paris goal of limiting global heating to as close to 1.5C as possible. Instead, they say, the credits are a fudge that cuts what Australia needs to do to meet its 2030 emissions target roughly in half and that Australia can claim access to them only because it set itself unchallenging targets under the Kyoto deal.

At the hearing, the Greens senator Sarah Hanson-Young asked if the department knew of any other country planning to use carryover credits to help them meet their Paris climate targets.

Kushla Munro, a first assistant secretary with the Department of the Environment and Energy, said: “At this stage, we are not aware of other countries intending to use carryover.”

“So just Australia?” Hanson-Young asked. “At this stage, yes,” Munro said.

Officials confirmed that to meet its 2030 Paris target, a 26% to 28% cut compared with 2005 levels, Australia would need to cut emissions by 695m tonnes cumulatively across next decade. They said 367m tonnes would come from the credits carried over from the previous Kyoto agreement.

Kyoto credits are not included in the Paris deal, but it is possible Australia could claim them unless they were ruled out through a consensus agreement by all countries involved in UN climate negotiations.

In its evidence at Senate estimates, the department suggested the government might not need to use the credits to meet its 2030 target if emissions from electricity generation continued to fall. Jo Evans, a department deputy secretary, said there had been improvements in emissions from the electricity sector year-on-year.

“There is some probability that the baseline level of projected emissions will be coming down and it’s quite possible that not all – if any – of that carryover will be needed in the end,” Evans said.

This assessment is at odds with several analyses, including one from the government, that found Australia is not on track to meet its Paris target.

While emissions from electricity have fallen in recent years, total national emissions have been rising since 2015, largely due to increases from natural gas production for export and transport.

Australia bettered its first Kyoto target, which allowed an 8% increase in emissions between 1990 and 2010, and is on target to meet its second Kyoto target, a 5% cut below 2000 levels by 2020. Neither target was consistent with what scientists said the country should be doing to play its part in addressing the problem.

The government’s Climate Change Authority recommended Australia should also be doing more by 2030 than it has promised, recommending a minimum 45% cut below 2005 levels if it is to play its part in a deal to limit global warming to less than 2C.

Department officials confirmed in Senate estimates that 92m tonnes of the emissions reduction needed to meet Australia’s target was projected to come from “technological improvements” not linked to policy changes but expected through unspecified innovations across the economy.