Two vessels at the centre of Scotland's ferry fiasco are to carry nearly 300 passengers fewer than contracted for to meet safety standards, it can be revealed.

The two lifeline ferries Glen Sannox and Glen Rosa were both due to hold up to 1000 passengers when they eventually come into services.

But it has emerged that to secure a safety certification and approvals from the Maritime and Coastguard Agency (MCA), which is responsible for implementing British and international maritime law and safety policy, the maximum carrying capacity is set to be cut to 852.

It is understood that the government-owned ferry owning and procurement agency Caledonian Maritime Assets Ltd (CMAL) and operator CalMac are considering the position.

It is said to be required to allow for improved passenger seating layouts.

Nationalised Ferguson Marine has said it has had to make "significant changes" to the designs for the stairwells and passageways to secure safety certification.

The new design affects the passengers and crew areas on three decks.

Ministers have said that a reduced passenger capacity is expected to be accepted through contract amendments.

The Herald: The delayed vessel is the sister ship to the Glen Sannox

It came as new concerns surfaced over the delivery of Scotland's ferries after the Scottish Government's ferry owners and procurers indicated they will not accept delivery if not fully dual fuel.

It comes as it emerged there have been questions from within nationalised Ferguson Marine about whether issues regarding the use of liquefied natural gas (LNG) could be a risk to the project.

The two lifeline ferries, Glen Sannox and Glen Rosa were to be able to operate on LNG which the Scottish Government ferry owners and procurers Caledonian Maritime Assets Ltd (CMAL) said was "significantly cleaner and will help to reduce emissions to meet ambitious Scottish Government targets".

After a series of issues with the 'green' fuel, Ferguson Marine's chief executive David Tydeman said in his latest update that while steady progress was being made with the LNG system "we still have some risks associated with the final installation of the special, low temperature pipework by the contractor".

It has emerged that CMAL has said that it won't take delivery unless the LNG system is working.

In a May update, Ferguson Marine's ship delivery director Andy Crossan said that at that point they did not have approval on the LNG system and were "working with contractors to de-risk".

Concerns have also been raised that regulatory clearances for the two fiasco ferries at Ferguson's were not made in good time - after it emerged they failed to comply with safety rules that are seven years old.

Safety clearances for both ferries were rejected on June 1, sparking a redesign and leading to the changes which led to cuts in passenger capacity for both vessels.

Among the issues that were to be resolved surrounded evacuation routes on the ships in order to satisfy the Maritime and Coastguard Agency (MCA).

Edward Mountain, convener of Holyrood's transport committee said: "Islanders have not accepted there is going to be less passengers and the fact that we're in this situation is because Ferguson Marine only spoke to the Maritime Coastguard Agency in June of this year, about whether the boats met the specification that they set out, based on 2016 dated regulations. So what we've got is late ferries, under capacity and over budget."

The extra work to meet MCA standards has led to a further rise in costs and delays to delivery.

The capital costs of the two ferries is now estimated to be approached £370m - although this does not take into account the taxpayer millions that are pumped into Ferguson Marine for running costs.

A ferry user group official said: "The fiasco around the delivery of these vessels just keeps getting more and more farcical.   Quite how we are in a position that we are having to cut the capacity of these much-needed ferries is beyond belief."

Four other ferries being built in Turkey are expected to be operational by 2026.

Transport minister Fiona Hyslop has told the Scottish Parliament: "What they (islanders) want is to have resilience in the fleet. They want not just two ferries they want all six ferries, and those six ferries will be completed by 2026 will provide the resilience in the fleet.

"What they don't want are speculative headlines that undermine the understanding that the vast majority of ferries in Scotland do run to time that there are far more passengers being carried than ever before. And there are far more routes than ever before. That doesn't help when there are issues and we're going into a period of dry dock which will put more pressure on the system. "