DEFENCE Secretary Philip Hammond has given the starkest warning yet that the UK would not build its new generation of warships on the Clyde if Scotland becomes independent.

In a speech to military top brass and business leaders in Edinburgh, he stressed contracts for the Navy's new Type 26 frigates would benefit "UK industry".

He also warned that an independent Scotland would not commission enough new vessels to keep Scots yards in business.

The warning came as he used his first speech in Scotland as Defence Secretary to launch a scathing attack on the SNP's military plans.

He claimed Scotland would be less well defended under independence than it is at present as part of the UK.

He also questioned whether an independent Scotland would be admitted to Nato and, in a message that will resonate south of the Border, he insisted Scottish independence would weaken the defence of the rest of the UK as the present integrated military would be lost as Scotland created its own "fledgling forces" from scratch.

His comments came as the launch of a newly-built warship from the River Clyde had to be postponed due to a ‘technical issue’.

The Type 45 Destroyer Duncan was due to leave BAE System's Scotstoun yard in Glasgow and journey to Portsmouth Naval Base where it will be officially commissioned into the Royal Navy.

The shipbuilder did not give specific details of the problem but said it is working with the Ministry of Defence (MoD) to resolve it and anticipate the ship will leave the yard in the next few days.

Duncan is the last in a 13-year, six-ship contract with the MoD. The other Destroyers are Diamond, Daring, Dauntless, Dragon and Defender and the fleet is set to serve the Navy until 2040.

Mr Hammond's shipbuilding warning also came ahead of a visit to Rosyth, where the Royal Navy's new aircraft carriers are being assembled.

He said: "It is worth noting that, other than procurement activity undertaken during the World Wars, no complex warships for the Royal Navy were constructed outside the UK in the 20th Century and the UK Government remains committed to using the strengths of UK industry in this specialist area."

SNP plans to build new frigates for the Scottish Defence Force would not sustain the Clyde yards, he insisted, adding: "In other words, despite the bluster, an independent Scottish Government would have to close Scotland's shipyards and procure its replacement warships either in the UK or abroad."

Attacking the SNP's "insultingly vague" defence plans he claimed their promised £2.5 billion defence budget could not support a military set-up capable of protecting the country as well as the UK's armed forces.

That sum, he said, would not deliver their promise of a 15,000- strong regular force plus an intelligence service.

He also dismissed SNP plans to demand a share of UK military hardware as a "chocolate bar approach" that would not provide a coherent military force by breaking off "one-sixth of an aircraft carrier as well as under one Red Arrow".

Warning of the limited career opportunities offered by the SNP's proposed Scottish Defence Force, he claimed: "It is a significant gamble to assume that troops in our UK armed forces would volunteer for a Scottish Defence Force."

He added: "The SNP are asking the Scottish people to vote for independence on a wing and prayer. But a wing and a prayer is no way to keep the people of these islands safe and secure."

On Nato, he said the UK played a leading role in the military alliance thanks partly to its nuclear deterrent.

He said: "A real question for proponents of independence is, how would an independent Scotland argue for membership at the same time as opposing nuclear weapons and seeking the removal from its territory of the UK deterrent, part of the Nato security umbrella?"

Mr Hammond's visit followed anger over the MoD's U-turn on plans to base 6000 extra troops in Scotland. Instead, numbers will rise by about 600.

SNP defence spokesman Angus Robertson accused the Defence Secretary of "attacking the SNP and Scotland".

He added: "Independence offers the attractive full-rank career prospects in Scotland which is impossible with the current set-up.

l Conservative Party chairman Grant Shapps has been quoted as asking "why in the heck would the Conservative Party be campaigning to keep the union with Scotland?"

But he said his party was committed to keeping Scotland in the UK because it was in the national interest.