A plan for disarming Trident missiles within days of independence and ridding Scotland of nuclear weapons within two years has been welcomed by Scottish ministers.

A practical guide on how to dismantle the Trident nuclear weapons system and remove it from the Clyde, produced by anti-nuclear campaigners, has also been pronounced credible by leading international experts on nuclear weapons.

The guide says the Vanguard-class submarines armed with Trident missiles could all be recalled to the Faslane naval base on Gareloch, and have their warheads disarmed within a week. After eight days, all of their missiles could be disabled.

Within a year, all 220 nuclear warheads at Faslane and the nearby Coulport armaments depot on Loch Long could be disabled. Within two years, the warheads could be removed from Scotland by road, and within four years they could all be dismantled.

The guide – to be published by the Scottish Campaign for Nuclear Disarmament (SCND) today – has been warmly welcomed by the Scottish Government. "We are firmly committed to the earliest possible withdrawal of Trident from Scotland, and to the pursuit of a world which is free from nuclear weapons," a government spokeswoman told the Sunday Herald.

"The suggested timetable is a welcome indication of how quickly Trident could be removed once Scotland has the powers to decide its own defence and security policy, and we note that various international experts have highlighted a credible timetable."

The Scottish Government is, however, committed to keeping the Clyde bases going. It wants "the development and diversification of HM Naval Base Clyde as a vibrant and sustainable conventional naval base in an independent Scotland," the spokeswoman added.

She pointed out that a clear majority of Scottish opinion was opposed to the UK Government's plans to keep Trident. "Yet the UK Government wants to use Scottish taxpayers' money to pay for these weapons of mass destruction, whilst the numbers of military personnel in Scotland continue to be reduced and Scotland's regimental traditions remain under threat."

To launch a Trident missile, a submarine captain has to turn a key, and a senior engineering officer has to press a trigger. The key and the trigger, kept in separate safes, could be removed from the submarines and stored at a secure site on shore, the SCND report says.

That could be done as soon as the submarines berthed at Faslane, and completed within seven days. It would only take one more day to make sure all the missiles were disabled by removing their guidance and flight control systems.

The next step would be to remove the multiple nuclear warheads from the missiles on the submarines, which is already done at Coulport for maintenance. Of the four Vanguard-class submarines, three are usually armed, while the fourth is being refitted.

The 40 warheads carried by a single submarine can be removed in as little as seven to 10 days, but SCND allows eight weeks for removing them from the three armed submarines to ensure it is done safely. Within ten weeks, the missiles themselves could also be removed from the submarines.

It would take up to a year, however, to disable all the warheads by removing three vital components – their arming, fusing and firing systems, gas transfer systems and neutron generators – and exporting them from Scotland. As well as the 120 "operationally available" warheads carried by submarines, there are an additional 100 warheads stored at Coulport.

SCND estimates it would take two years to get rid of all the warheads by transporting them south in 24 armed road convoys, each carrying eight or nine warheads. Prior to be dismantled, some could be stored at a special ammunition store at RAF Honington in Suffolk, which was used to keep nuclear weapons in the 1970s.

Convoys already routinely carry warheads between Coulport and the nuclear bomb factories at Aldermaston and Burghfield in Berkshire for maintenance. According to SCND, the warheads could all be dismantled within four years at Burghfield.

"Almost 60 years since the first British nuclear test in October 1962, we are now for the first time in a position where we can seriously consider the practical steps which need to be taken to dismantle Trident," said SCND's co-ordinator, John Ainslie.

"This report shows that we could, in days, remove the risk that Trident could ever be used in anger. Within two years Scotland could be free of all nuclear weapons, and two years later all of the warheads could be completely dismantled."

Dismantling Trident would save the UK Government from wasting £100 billion on nuclear weapons over the next 50 years, Ainslie argued. There was nowhere in England or Wales where Trident could be successfully relocated, he claimed.

He added: "Disarming Trident would not just by welcomed by the vast majority of Scots, it would also give many people in England and Wales something to cheer about as well."

The SCND report is based on solid evidence and is "highly credible", according to Bruce Blair, one of the world's leading experts on de-alerting nuclear forces. He was a launch control officer for US Minuteman nuclear missiles and co-founded the "Global Zero" disarmament initiative.

"It accurately describes the essential steps needed to remove Trident submarines from alert status, de-activate the weapons systems, and remove them from Scottish territory. If anything, the timetable is somewhat conservative," he said.

"My studies have determined that many of the steps could be taken at a pace that is nearly twice as fast, though the more leisurely pace in the SCND timetable ensures a completely safe process of dismantlement."

Richard Garwin, another leading US nuclear weapons expert who designed the first H-bomb, thought the SCND timetable was possible. "The missiles and nuclear weapons can be disabled within weeks and removed within two years and dismantled within four years, if that were judged to be desirable and the decision made to do so," he told the Sunday Herald.

The SCND timetable was described as "not unreasonable" by Frank von Hippel, a former White House nuclear adviser who is now professor of international affairs at Princeton University.

According to professor Malcolm Chalmers, defence policy director at the Royal United Services Institute for Defence and Security Studies in London, the proposed timetable was "broadly credible in technical terms".

But he added: "It would amount to a forcible demobilisation of the UK's nuclear force, since it would almost certainly take place against the wishes of the government in London, and it would not provide it with enough time to build alternative facilities for housing Trident submarines."

The UK Government argued that Scotland benefits from being part of the UK, and the UK benefits from having Scotland within it. "No plans for independence are being made as the government is confident that people in Scotland will continue to support the UK in any referendum," said a UK Government spokesman.

"We are therefore not making plans to move the nuclear deterrent from HM Naval Base Clyde. The government is committed to maintaining a continuous submarine-based nuclear deterrent and has begun the work of replacing our existing submarines."