Nick Clegg has been accused of trying to pretend the Liberal Democrats have nothing to do with signing off arms sales to Israel, even though Vince Cable, the Lib Dem business secretary, is in charge of approvals. Alistair Burt, a former Conservative Foreign Office minister for the Middle East, said the Lib Dems should not be trying to distance themselves from the issue, after the deputy prime minister called for some licences to be revoked if they had been used for repression in Gaza.

"I think, to be blunt, they are trying to pretend that Liberal Democrats don't sign off arms exports to Israel, which they have been doing," he told the BBC's World at One. "Vince Cable has been doing that for the past few years, because it's a joint decision he takes with the foreign secretary. I hope he will have assured himself that any exports to Israel are for their external protection and security."

Burt said it was "no bad thing" to review arms exports but the UK already had strict controls. "This country does not export goods to any country which could be used for internal repression. That is in the law. The law is carefully scrutinised, not least by an extremely good Commons committee headed by Sir John Stanley," he said.

Stanley, chair of the parliamentary select committees that oversee British arms exports, has asked the foreign secretary, Philip Hammond, for details of any military exports that may have been used by the Israeli army in Gaza. He also asks Hammond for more details of the government's review of arms export licences, which was announced this week.

On Thursday, Clegg made clear he thought Britain should immediately revoke any licences for arms that had been used in the conflict. However, he stepped back slightly from arguing for the suspension of the sale of all military equipment to Israel, saying this should only happen if the ceasefire broke down.

Clegg has made clear already that he favours an arms embargo, but he set out his thinking more clearly in an LBC radio phone-in. "We must respect the strict criteria laid down in law," he said. "We must look at what's happened in Gaza to see if those criteria were breached … If it's shown those criteria were breached, then never mind suspending those licences, they would have to be revoked."

Clegg said no new arms export licences had been issued during the past month of violence but there could be a complete suspension if Israel and Hamas returned to violence. "We now have a truce. I think it is crystal clear and it would be unacceptable and wholly wrong for us to do anything other than suspend those licences if that ceasefire were to come to an end and violence were to break out again," he said.

Senior Conservative figures including Andrew Mitchell and Sayeeda Warsi, who resigned as a foreign minister over the crisis, have said there must be an embargo.

Clegg is the only party leader to call for direct talks between Israel and Hamas, a proscribed terrorist organisation. Labour's shadow foreign secretary, Douglas Alexander, said this was "misguided" and wrong on Thursday, but Clegg's position was backed by former Liberal leader David Steel, who also said Israel's government was "treating Palestinians as lesser human beings in exactly the same way the South African apartheid government treated the majority of its citizens".

David Cameron is under pressure to take stronger action against Israel after the UN condemned its shelling of a school as a moral outrage. The prime minister has not so far joined Clegg or Ed Miliband, the Labour leader, in saying Israel's actions in Gaza have been disproportionate.

The total value of controlled export licences to Israel – which can be for commercial or military use – was around £8bn last year. The government and campaigners agree that the vast bulk of this – around £7.75bn – is for commercial equipment, mostly cryptographic software to supply Israel's for mobile phone networks.

Documents obtained by the Campaign Against Arms Trade under the Freedom of Information Act reveal that since 2010 there have been £42m worth of licences to export military-only equipment to Israel.

Licences granted in the past year include a wide range of hardware, from components for naval guns and drones to ammunition, submarines and combat aircraft parts.