The US is unlikely to deliver any nuclear-powered submarines to Australia, former prime minister Malcolm Turnbull is to tell an independent inquiry into AUKUS, arguing the superpower would not be able to build enough Virginia-class vessels to honour its commitments to the defence pact.

Describing AUKUS as a “bipartisan error”, the long-term AUKUS critic will today tell the crowd-funded public inquiry chaired by former Labor minister Peter Garrett that the second-hand submarines would be transferred only if the sale does not degrade US undersea warfare capabilities and that the industrial base can support both nations’ needs.

In a submission provided in advance of his appearance, Turnbull says the US must build more than two nuclear-powered submarines a year by 2029 to supply its own navy and Australia’s: “The prospect of the US doubling its rate of Virginia production in the next six years is highly unlikely. So there is a very real risk Australia gets no Virginias at all. This risk is acknowledged everywhere but in Canberra. There is apparently a view that if anyone were to openly contemplate a Plan B (what to do if no submarines arrive) this might discourage the Americans from selling us any.”

Top US and Australian officials have conceded that the three submarines may not be delivered on time, even now that Australia has agreed to buy second-hand vessels. However, both administrations insist that the subs deal is a top defence priority.

Deputy Prime Minister Richard Marles in June said increasing US submarine production was a challenge, but doable, as Australia had dispatched up to 130 tradespeople to help with production bottlenecks.

Top US Pentagon official Austin Dahmer told a hearing on Capitol Hill last month that billions in extra funding from both governments had not hastened delivery, but also told this masthead: “We’re full steam ahead … It’s incumbent on all parties – us and the Australians and the British as well – to ensure that we’re meeting those conditions on the timelines agreed upon. It’s a conditions-based agreement; it’s not a time-based agreement. So we have time to improve – we’re just being clear well ahead of time that we’re not there yet.”

Turnbull’s submission describes the Virginia-class submarines as a “fragile stop gap” between the retirement of Australia’s conventional Collins class submarines and the arrival of bespoke AUKUS submarines built in the UK some time in the 2040s.

Turnbull says Australia risks “a period of zero submarine capability” under the AUKUS arrangement. “This would be the most serious failure of Australian defence planning in modern history.”

Last month, former Liberal defence minister Christopher Pyne, now a lobbyist with many defence industry clients, told the inquiry he didn’t think the US submarines would be delivered on time.

“Do I think they’ll deliver it on time and on budget? No, I don’t. I can say that now because I’m not in public life any more, but I don’t think they will ... I think they’ll give it a good go.”