An archive picture of HMS Montrose at sea (Picture: Royal Navy).
A former Navy chief has called for the UK to speed up building more frigates, in the wake of an attempt by Iranian boats to impede a British oil tanker near the Gulf.
Lord West of Spithead, former chief of naval staff and First Sea Lord, said Britain currently had too few frigates.
At Lords question time, the Labour peer warned:
"It makes us less secure. It means wars are more likely and it's really important to move forward."
Defence minister Earl Howe said the actions of HMS Montrose, in driving off the Iranian boats, demonstrated that "we have the right assets in the right places".
Lord Howe told peers the Government's priority was to reduce tensions in the region.
HMS Montrose, a British frigate shadowing the tanker, was forced to move between the three Iranian boats and the tanker.
Iran had threatened to retaliate for the seizure of one of its own tankers, but denied any attempted seizure.
Lord Howe said ministers remained committed to a surface fleet of at least 19 frigates and destroyers, adding:
"The Royal Navy will have the ships it requires to fulfil their policy commitments."
But Lord West, a former security minister, said that of 13 frigates, only eight were effectively available for operations by this "great maritime nation of ours".
He said the nearest major warship to the one in the Gulf was "the other side of Suez, which I find rather worrying".
Turning to orders for new ships, Lord West said the Ministry of Defence should look as a matter of urgency at speeding up the build rate of type-26 frigates "because we have too few as a nation".
Tory Duke of Montrose also asked if Britain had enough of these "very effective vessels" to ensure security.
Lord Howe said the Government kept fleet deployments under constant review to adapt to evolving situations in the Gulf and elsewhere.
For the Opposition, Lord Tunnicliffe asked if the incident would require the deployment of more ships in the Gulf and, if so, what "task" would be left "uncovered".
Lord Howe said at the moment ministers thought they had the "right assets in the right places" but this was kept under review.
Later, Baroness Goldie, for the Government, said: "We remain concerned by heightened tensions in the Gulf of Oman and continue to call for de-escalation on all sides."
Lady Goldie said the Government had long made clear its concerns about Iran's "destabilising regional activity".
Tory former minister Lord Bates warned that the prospect of a military confrontation with Iran had "potentially catastrophic consequences".
He called for every effort to be made, despite "all the provocations," to seek a peaceful diplomatic solution to the "crisis".
Lady Goldie said Britain was in contact with the US and other international partners, adding:
"Our priority remains finding diplomatic solutions to de-escalate the tensions in the region."