The Foreign Office has failed to apologise after Baroness Warsi provided Parliament with a vastly inflated number of Palestinian civilians killed by Israel.

A spokesman said a “clerical error” was to blame for the claim that there had been more than 3,600 fatalities since January 2012.

The senior minister had provided the response to a Written Parliamentary Question posed by Baroness Tonge, who had asked whether the government had a record of the number of “non-violent protestors killed and injured” in the Palestinian territories since 2002.

Responding, Baroness Warsi initially said “no assessment” of that nature had been recorded.

But she added: “According to the website of the UN Office for the Coordination of Humanitarian Affairs, 3,643 Palestinian civilians have been killed by Israelis since 1 January 2012 in incidents directly related to the Israeli/Palestinian conflict in the West Bank and Gaza strip.”

Clarifying the remarks on Wednesday evening, a Foreign Office spokesman said the answer “should have stated 2005 not 2012”.

The Foreign Office took more than 24 hours to provide an explanation for the error, and offered no apology. Instead it said Baroness Warsi would write to Baroness Tonge “to correct the response”.

Baroness Warsi has not commented on the matter.