A political row has broken out over delays to the construction of eight new ships for the Royal Navy due to be built on the Clyde.

Nicola Sturgeon and Scottish Tory leader Ruth Davidson became embroiled in a spat on social media after a meeting of the Commons Defence Committee revealed there is still no start date for work to begin on the Type 26 frigates.

The ship contracts were promised to Scotland before the independence referendum when the future of shipbuilding on the Clyde became a key issue.

READ MORE: MOD denies money shortage causing delays on the Clyde in the construction of Navy frigates

Tony Douglas, the Ministry of Defence's top official responsible for military equipment told the committee on Wednesday he could not give a "time or a date" for the design of the ships being approved.

The First Minister then tweeted: "If true, this is a disgraceful betrayal of the Clyde shipyard workers - and a breach of the promise made in #indyref."

Ms Davidson later wrote: "Remind me again of the number of warships you planned to build in an independent Scotland? Zero, right?"

READ MORE: MOD denies money shortage causing delays on the Clyde in the construction of Navy frigates

The pair then exchanged several tweets during which Ms Sturgeon accused the Conservative leader of "deflecting" and dodging responsibility, and Ms Davidson said the First Minister appeared to be unable to answer a single question.

The dispute also centred on whether or not the design of the ships, which is said to be just 60 per cent complete, was causing the delay.

The defence committee was previously told that a shortage of money had caused the delay to a start date for the build, however, Mr Douglas said on Wednesday it was due to the design being incomplete.

READ MORE: MOD denies money shortage causing delays on the Clyde in the construction of Navy frigates

"If you were building an extension on the back of your house, you wouldn't get it priced if it was only 60% designed," he said.

"We are in a good place right now, but with 60% design fixity, this is about driving it to closure, which is the road we are on."

This point was also raised by Ms Davidson, who asked Ms Sturgeon: "Are you really suggesting building should start before design phase complete - or that ministers are in charge of design?"

However, shipbuilder BAE Systems responded that the design being incomplete would not delay a start date for work to begin.

A spokeswoman for the firm confirmed that projects regularly proceed with an incomplete design and said BAE is working with the government to agree a production schedule.

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She added: "We have an agreed design with the Ministry of Defence for the Type 26 ships, with a high level of design maturity and we have met all design maturity milestones to date.

"We are confident that we will be ready to move into the manufacturing phase with a very high level of design maturity in line with the production schedule to be agreed with the Ministry of Defence."

The UK Government said it was "committed" to building ships on the Clyde and to the Type 26 programme.

A government spokeswoman said: "Over the next decade, we will spend around £8 billion on Royal Navy warships and, because Scotland voted to remain part of the UK in 2014, will continue to be an important manufacturing base for them."