Mr Mabhouh was murdered in a Dubai hotel room
Another two British passports have been linked to the assassination of a Hamas militant in Dubai.
Foreign Office Minister Chris Bryant insisted the government had had no prior knowledge of the killing or use of the passports.
It was already known six fake UK passports were among those used by the alleged killers of Mahmoud al-Mabhouh.
Earlier, Foreign Secretary David Miliband urged Israel to co-operate with a UK investigation.
The Israeli secret service Mossad has been widely accused of carrying out last month's killing but Israel has repeatedly asserted there was no proof its agents were involved.
Mr Mabhouh, one of the founders of Hamas's military wing, was found dead in a Dubai hotel room on 20 January and an autopsy report said he had been electrocuted and then suffocated.
Responding to an urgent question in Parliament, Mr Bryant said the authorities in the United Arab Emirates had sent details of "at least" two passports which could be linked to the assassination.
He also set out the timetable of what ministers were told and when about the original six passports.
Mr Bryant said the Emirati authorities had told British officials on 31 January that European passports had been used by the killers.
On 12 February, they were told UK passports "might" have been involved and this was confirmed three days later, just hours before the Dubai police released the names and passport photographs of 11 suspects.
There has been speculation that the government and the UK's intelligence service MI6 were tipped-off about the operation.
But Mr Bryant emphasised that "no part of the British government, either minister or official, had any foreknowledge of Mr al-Mabhouh's killing or the use of British passports in it".
"To suggest otherwise is to make an irresponsible allegation without any basis in fact," he added.
Shadow foreign secretary William Hague, who tabled the question, asked if the two additional passports were diplomatic, following indications from the Dubai authorities, but this was denied.
Mr Bryant was speaking after Mr Miliband held a 45-minute private meeting with his Israeli counterpart Avigdor Lieberman in Brussels.
The foreign secretary said Mr Lieberman had "no information to give at this stage" about the incident, which has sparked a diplomatic row between the two countries.
Six British-Israelis had their passports cloned and new pictures inserted
"I obviously went through the importance of the investigation the prime minister has announced and the importance we attach to Israel's co-operation with that investigation," Mr Miliband said.
"It is very important that people know we continue to take this issue very seriously indeed. There is very real concern across Europe."
The UK government has ordered the Serious Organised Crime Agency to carry out a full investigation into the use of the passports, which carried the names of six British-Israelis.
They are to be given new passports by the British embassy.
In addition to the UK passports, it is known the hit squad also used Irish, German and French passports.
All the European Union foreign ministers, who were in Brussels for a pre-arranged meeting, "strongly condemned" the use of forged EU passports.
In a joint statement, they said: "The killing of Mahmoud al-Mabhouh in Dubai raises issues which are profoundly disturbing.
"We strongly condemn the use of fraudulent EU member states' passports and credit cards acquired through the theft of EU citizens' identities."