Lahoud was interviewed as a witness by two UN investigators at the presidential palace late on Friday, a statement from his office said.
This was confirmed by a separate statement issued by the UN commission's investigative body which added he was not a suspect.
Lahoud has been under the spotlight since last August when the Lebanese authorities arrested three former security chiefs and the current head of the republican guards Mustapha Hamdan.
All four figures are considered close to the president.
Pressure on the president to step down further intensified after October's UN report, which stated that Lahoud received phone calls from a suspect shortly before the massive bombing that killed al-Hariri.
"The president told [investigators] the true and accurate information concerning what has been reported about phone calls to the presidential palace before and after the deplorable crime," said the presidential office in a statement.
The UN report has strengthened the position of a number of Lebanese politicians who have routinely accused Lahoud of being a symbol of Syrian tutelage and called on him to step down when the Syrian military withdrew from the country last April.
"If he is left with just a bit of sanity, he would resign tomorrow," Dory Chamoun, the head of the National Liberal Party, one of the main Christian parties, told Aljazeera.net.
"The republic is more important than its president," MP Elias Atallah, the head of the Democratic Left Movement party, said shortly after UN investigators met with Lahoud.
"Lahoud should just resign and spare the presidential post from such scrutiny."
Maronite Council objects
However, a call by the Council of Maronite Bishops to halt the campaign aiming at discrediting and ousting the president surprised many Lebanese.
Mehlis' UN report implicated four
of Lahoud's aides in the killing
The council, which was the most vocal opposition to the Syrian presence in Lebanon, issued a vaguely worded statement interpreted by many as supporting the president, who is also Maronite.
"The current dispute over whether the president should remain or vacate his position has put Lebanon in an awkward situation. The presidency should remain above this dispute," the council said in the statement.
The statement added that the Lebanese Constitution "in such cases has the decisive word", a phrase that many interpreted as support for Lahoud to complete his term.
But Chamoun believes the council overplayed its hand in hinting Lahoud deserved constitutional protection.
"Lahoud was the first person who failed to respect this same constitution," he said.
Lahoud's presidency has been in question since September 2004, when Syria pressured the Lebanese parliament to amend the constitution and extend his term for another three years.
Lahoud has repeatedly said he would remain in power "in accordance with the constitution".
Political writer Nasseer Asaad told Aljazeera.net the Council of Maronite Bishop's position was reflective of the political power struggle between prominent Maronite politicians.
He said Syria's pullout facilitated the return of two rival Maronite leaders to the political scene.
General Michel Aoun, head of the Free Patriotic Movement, returned to Lebanon from a 14-year exile in France, and Samir Geagea, the leader of the Christian Lebanese Forces, was released after 11 years in prison.
"Any struggle over who will be the next president will only lead to struggle among Maronites," said Asaad.
Aoun surprise move
But Aoun surprised many Lebanese when he allied with pro-Syrian politicians, including Lahoud's protégés, during the parliamentary elections in June.
In 1989, he waged a fierce "War of Liberation" against Syrian troops in Lebanon but was defeated and exiled to France in 1990.
Aoun allied with pro-Syrian
politicians in the June elections
Throughout his stay in France, Aoun repeatedly described Lahoud and the successive governments that ruled the country under Syrian domination as "puppets" in the hands of Syria.
But since his return, Aoun has refused the prospect of ousting Lahoud. He recently told the BBC Radio's Arabic Service that Lahoud would only resign if "I am the next president".
He alluded to Lahoud's understanding that an Aoun presidency would shield him from possible prosecution in the al-Hariri investigation.
Weakened Christian position
In an article published in the Lebanese daily An-Nahar newspaper, MP Gebran Tueini said he understood the council's apprehension over ousting Lahoud.
He believed Lahoud leaving office would weaken the influence of Christian politicians, particularly those who are Maronites.
The article, titled The Battle to Liberate the Presidential Post, however, warned that Lahoud's stubborn grip would only increase the political isolation of Christians.
In a sign that Lahoud may be internationally shunned, he was not invited to next month's Euro-Mediterranean Summit in Barcelona.
Lebanon will be represented by Sunni Prime Minister Fuad Siniora instead.
"What crime did the Christians, and specifically the Maronites, commit to deserve political isolation?" Tueini asked.
Under Lebanese Constitutional law and the country's confessional system of distribution of power, the presidency has always been reserved for the Maronites.
The position of prime minister is always reserved for a Sunni Muslim while the Speaker of Parliament is always a member of the Shia Muslim community.