(CNN) -- Syria has agreed to permit U.N. investigators probing the assassination of former Lebanese Prime Minister Rafik Hariri to question five of its intelligence officers in Vienna.The development -- disclosed Friday at a news conference in Damascus, where Deputy Foreign Minister Walid Moallem spoke to reporters -- broke a deadlock with the United Nations that had brought increasing pressure on Syria.German prosecutor Detev Mehlis is heading the U.N. investigation into the February 14 assassination of Hariri, who was killed with 20 others in a Beirut truck bombing.Mehlis' commission issued an interim report last month that implicated Syrian and Lebanese intelligence services in the assassination.Moallem told reporters that the breakthrough came after Syria received "guarantees concerning the rights of the individuals" and assurances that Syrian sovereignty would be respected, The Associated Press reported."The (Syrian) leadership has decided to inform Mehlis that it accepts his suggestion, as a compromise, that the venue to listen to the five Syrian officials be the U.N. headquarters in Vienna," AP quoted Moallem as saying.The question of the venue had led to a delay in the probe.Investigators wanted to question the intelligence officers outside Syria, but Syria had not permitted officials wanted for questioning to leave home soil.It is thought Syria was concerned that if they were questioned in Lebanon, Mehlis could have recommended the arrest of the officials there. Lebanon has detained other suspects at Mehlis' request.It is not yet clear when the questioning will take place. "We will contact the (U.N.) commission very soon to specify dates and agree on the procedures and all that is necessary," AP quoted Moallem as saying.Moallem did not identify the five people to be questioned, saying it was a matter of the "secrecy of the investigation." He said only their lawyers would accompany them to Vienna, AP reported.Mehlis' spokeswoman in New York, Nasra Hassan, said the prosecutor welcomed the Syrian announcement, and U.N. spokeswoman Marie Okabe said Secretary-General Kofi Annan was pleased with the agreement."(Annan) expects their cooperation to continue throughout Mr. Mehlis' investigation," AP quoted Okabe as saying.The U.N. Security Council has warned Syria of "further action" -- diplomatic language for sanctions -- if it fails to cooperate fully with Mehlis.Hariri's assassination provoked mass demonstrations in Lebanon calling for Syria to pull its troops from the country, where they had been stationed since the 1975-90 civil war.As international pressure mounted, Syria withdrew its troops in April. In subsequent months, Lebanese voters elected their first parliament in years that did not have a pro-Syrian majority.Copyright 2005 CNN. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed. Associated Press contributed to this report.