Iran's Deputy Foreign Minister Ali Ahani has held talks in London with UK Foreign Secretary Jack Straw on the arrest of the former Iranian ambassador to Argentina by British police.
The Foreign Office says the matter is out of government hands
Mr Ahani called for the release of the former ambassador, Hadi Soleimanpour, who is studying in England.
He is wanted by police in Argentina in connection with the bombing of a Jewish community centre in Buenos Aires in 1994, in which more than 80 people were killed.
Argentina is seeking the extradition of eight Iranian officials in total over the bombing.
Mr Ahani said the Argentine court's request for Mr Soleimanpour's arrest was illegal and politically motivated.
But a UK Foreign Office spokesman told BBC News Online the British Government was not involved at any stage and any action is now a matter for the courts.
Iran denies any involvement in the bombing and has warned the UK of serious consequences if Mr Soleimanpour is not freed immediately.
Relations under threat
The UK Foreign Office denied the arrest was politically motivated, saying it was the result of international legal processes.
It added the future of bilateral relations is now in Iran's hands.
"Iran needs to understand Britain is a key voice for determining EU policy towards Iran. The Iranians are keen to
keep EU relations with Iran on track so it is in no-one's interests to have a fall out at this stage."
Arrest of Iranian diplomat
13 August - Argentine authorities issue arrest warrant
Warrant delivered by Interpol to UK police
Police present warrant to Bow Street Magistrates Court
21 August - Court issues warrant for arrest
Mr Soleimanpour arrested same day by Durham constabulary
UK Government not notified until after arrest (says FO)
24 August - Jack Straw tells
Iran's foreign minister he cannot interfere
"We don't want this issue to affect bilateral relations, we have made clear this is not a political issue and we must abide by our international obligations," the spokesman said.
An Iranian Government spokesman said Tehran hopes it will not come to the withdrawal of ambassadors, but he said all legal and diplomatic options were open.
Iranian officials have said they want the issue resolved by Friday.
But extradition cases can take months because the person being extradited can appeal against decisions.
The BBC's diplomatic correspondent, Barnaby Mason, says that while the UK Government is insisting that the extradition process is a matter for the courts and it cannot interfere, this is not entirely true.
In reality, extradition under British law is not a purely judicial affair - the final decision is made by the home secretary, but he gets involved only after the courts have given their ruling, our correspondent says.
At that point, the home secretary may consider political and other representations - for example, from the Foreign Office and the Iranian Government.
A few years ago, the English courts ruled that the former Chilean dictator, Augusto Pinochet, could be extradited to Spain, but the government then freed him on health grounds.
Meanwhile in Belgium, police have arrested a second former Iranian diplomat, Saied Baghban, also wanted by Argentina in connection with the bombing.
He was later released because of his diplomatic immunity, AFP news agency reports.