David Cameron has accused Argentina of "colonialism" in the wake of rising tensions over the Falkland Islands and insisted he will ensure the defence of the islands is "in order".

The prime minister, who was responding to a question in the House of Commons, also confirmed that the relationship with Argentina was discussed at length by the National Security Council (NSC) on Tuesday.

Cameron told MPs: "We support the Falkland Islanders' right to self-determination, and what the Argentinians have been saying recently, I would argue is actually far more like colonialism because these people want to remain British.

"I'm determined we should make sure that our defences and everything else is in order, which is why the National Security Council discussed this issue yesterday."

According to the Falklands' representative in the UK, Sukey Cameron, relations with Argentina have deteriorated markedly over the past year or so. A trade embargo by various South American countries - called for by the Argentine government - came into force earlier this month.

Under the terms of the embargo, vessels carrying the Falklands' flag are banned from docking in the ports of several South American nations, in a move the Falklands' government says is designed to stifle their economy.

This was followed by the Falklands refusing to allow an Argentine ship clearance to dock at the islands yesterday. The Falklands' government claimed it refused permission for the ship to land because some of those on board were suffering from the Norovirus vomiting bug.

Tensions have also risen with the increasing likelihood of vast oil reserves being found in the Falklands territory but [Sukey] Cameron, insists relations have been deteriorating for several years.

"The oil is an added excuse for them to raise the pressure," she said. "I don't think it's the cause, it's just an added excuse.

"This started last year with the presidential decree that made any ship transiting through Argentine waters to the Falklands to apply for a permit from the Argentine government to do so.

"What that did was put ship owners and charters off operating in the area. So whilst there have been no incidents or arrests as far as we're aware, the mere fact that they were threatening to arrest vessels that didn't have permits was enough to have an impact."

It is considered unsual for the NSC to meet to discuss a single issue, with Downing Street sources suggesting it sent out a "very strong signal" to the Argentine government.