In a move that threatens to strain diplomatic ties, Britain has blocked the sale of spare parts for Israel’s fleet of missile gunships because they were used in the recent campaign in Gaza.

The first country to revoke an arms licence in response to the war in Gaza six months ago, Britain told the Israeli Embassy in London that five of the export requests for parts for the Sa’ar 4.5 gunships had been rejected because the vessels had fired on Gaza during Operation Cast Lead, Israel’s controversial 23-day campaign against the militant group Hamas. The spare parts were intended for the ships’ guns.

An Israeli defence official said that Britain’s decision to revoke five of the 182 licences reviewed by the Government would not impair the navy’s operational abilities — but admitted that there was concern within the military that other countries might follow suit.

Officials in the Israeli Prime Minister’s office said the British ban was a “dangerous step for Israeli diplomatic relations”.

“There are people who will see this as a condemnation of the Israeli operation in Gaza. They will use the UK as an excuse to issue their own embargoes. This is not a situation Israel can accept,” they said.

An official at the Foreign and Commonwealth Office denied that the move amounted to a partial British arms embargo on Israel, but Avigdor Lieberman, the Israeli Foreign Minister, appeared to disagree. “Israel has known many cases of embargo in the past. We always knew how to get by, and there is no need to get excited about this,” he said.

After the Gaza war a number of MPs called on Gordon Brown to impose a complete arms embargo on Israel.

A petition of more than 38,000 signatures was posted on the Prime Minister’s website calling for the sale of all munitions to be banned. Earlier this year, Amnesty International highlighted Britain’s role in supplying engines for the Hermes 450 drone, an unmanned aircraft widely used by the Israeli military in Gaza.

According to the most recent statistics, Britain has more than tripled its sale of weapons to Israel in the past two years. In 2007 Britain sold arms worth £6 million to Israel while in 2008 it licensed arms worth £20 million in the first quarter alone.

The FCO in London said it was acting in accordance with European Union arms licence criteria and that export sales had been stopped in the past; both for Israel and other countries when the EU ground rules were perceived to have been broken.

“In light of Operation Cast Lead, and in line with our obligations after a conflict, we conducted a review of extant export licences for Israel,” the FCO official said. David Miliband, the Foreign Secretary, had announced the review in a statement to the Commons on April 21.

“We judged that, in a small number of cases, Israeli action in Cast Lead would result in the export of those goods now contravening the [EU’s] consolidated criteria. These licences have been revoked. This is standard practice. A number of licences to both Russia and Georgia were revoked following the Georgia conflict last August,” the official said.

He added: “There are no security agreements between the UK and Israel. We continue to assess all arms export licence applications against the consolidated criteria and the prevailing circumstances, which take into account the recent conflict.”

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