A senior Iranian diplomat is on his way to London for urgent talks aimed at defusing a brewing crisis over last week's arrest of a former Iranian ambassador to Argentina by British police.
Iran's Deputy Foreign Minister Ali Ahani will hold the talks with British Foreign Secretary Jack Straw, during his two-day visit.
No-one has been brought to justice over the 1994 bombing
The former ambassador, Hadi Solaimanpour, is wanted by police in Argentina in connection with the bombing of a Jewish centre in Buenos Aires in 1994, in which 85 people were killed.
Iranian leaders have protested strongly against the arrest of Mr Solaimanpour and warned of serious consequences for Iran's relations with London if he is not released soon.
Mr Ahani is trying to defuse this sudden crisis before it is too late.
Mr Straw has taken a special interest in Iran; he has visited the country four times since he took office.
As a former Home Secretary who dealt with the Pinochet extradition, Mr Straw knows more about such cases than most.
But he will find it hard to convince Mr Ahani that the British Government's hands really are tied when it comes to such matters.
Iranian leaders and officials across the board are convinced that the arrest is politically motivated, rather than part of a purely judicial process as British diplomats have tried in vain to insist.
Even the normally mild-mannered reformist president, Mohammed Khatami, issued an unusually robust warning on Sunday that Iran would take strong measures if Mr Solaimanpour was not freed immediately with an apology.
'Out of question'
Iranian officials have said they want the issue resolved by Friday.
If they are hoping the case will be dropped, that is clearly out of the question.
The most that might be feasible, at the discretion of the Bow Street court, would be the granting of bail.
Even that is looking unlikely; it has already been refused and there seems little at this stage to prevent this crisis from gathering pace.
An Iranian Government spokesman has said that Teheran hopes it will not come to the withdrawal of ambassadors.
But he said all the legal and diplomatic options were open.
British diplomats have made it clear that any steps taken against London over this affair would be likely to have wider repercussions for Iran's relations with the European Union as a whole.