"Those in charge recognized that non-diplomatic activities are being undertaken and announced that this diplomat should leave the soil of the Islamic Republic of Iran," Foreign Ministry spokesman Mohammad Ali Hosseini told a news conference.
A spokeswoman for the German Foreign Ministry told the DPA news agency on Saturday that a German diplomat had left Iran, but declined to say whether this was a tit-for-tat expulsion.
The Hamburg-based weekly Der Spiegel reported last month that Berlin had previously expelled an Iranian diplomat in July after he allegedly sought to purchase equipment for his country's controversial nuclear program.
The man, an attaché at Iran's embassy in Berlin, was reportedly in contact with a specialist firm in the southern German state of Bavaria in an apparent attempt to buy a piece of equipment which could also be used in uranium enrichment
The German Foreign Ministry declined to comment at the time.
Western nations have been pushing for Iran to halt uranium enrichment, which they fear could potentially lead to the production of atomic weapons and their placement in the hands of fundamentalists. Tehran insists that its nuclear program is for peaceful purposes.
In a recent article, which was both a look back at 2007 and a view to the upcoming new year, German Chancellor Merkel said heading off the prospect of a nuclear-armed Iran remained a "vital interest" for the world community.
She wrote that Iran's nuclear program is still "one of our biggest security policy concerns," and said Iran's refusal to suspend its uranium enrichment activities -- as demanded by the United Nations Security Council and the nuclear watchdog agency IAEA -- was dangerous.
"The unbearable rabble-rousing of the Iranian president [Mahmoud Ahmadinejad] against Israel also speaks volumes," Merkel wrote in the article published in the German business daily Handelsblatt on Firday, Dec. 28.
Reformists hope to mend ties
Meanwhile, Iran's reformist politicians pledged on Saturday to put an end to the ongoing crisis in relations with the West if they win the upcoming parliamentary elections.
"Following our internationally acknowledged legitimate right to pursue peaceful nuclear technology should go parallel with an active diplomacy," said Habibullah Bitaraf, one of the candidates of the reformist opposition coalition.
"If our diplomacy was right, then we would not have the current tensions with the West and the (UN) sanctions," he told a Tehran press conference.
The reformist parties in Iran have often criticized President Mahmoud Ahmadinejad economic and other policies, as well as his fiery, anti-Western rhetoric, which has brought the country on the verge of international isolation.
Registration for parliamentary elections
State television said prospective candidates started registering to stand in the election for the 290-seat parliament throughout the Islamic Republic.
Hopefuls have until next Friday to fill out a four-page application on an Interior Ministry Web site before going to the governor's office to complete the process, Iranian media reported.
All candidates, however, have to be approved by the hardline unelected Guardians Council, which has the right to disqualify any candidate it deems to be insufficiently qualified.
Voting will take place on March 14.