One of the men also is suspected of transferring money to a woman -- later killed in a French police raid connected to the probe -- four days after the attacks that killed 130 people, the Belgian federal prosecutor's office said.
Both men are believed to have been in a vehicle with Abdeslam at the Austria-Hungary border September 9, about two months before the November 13 attacks, the prosecutor's office said Friday.
Both men, the office said, used fake Belgian identity cards to cross the border with Abdeslam, whose identity also was checked there. Abdeslam's companions were using the false names Soufiane Kayal and Samir Bouzid, the office said.
The prosecutor's office did not elaborate on the purpose of the trip or say in which direction they were traveling. However, the office said Abdeslam twice visited Hungary's capital, Budapest, in September.
Investigators haven't detailed what they believe Abdeslam's role was in the Paris attacks, though Paris prosecutor Francois Molins has said he may have dropped off suicide bombers at the Stade de France just outside the capital, and then made his way to a Paris neighborhood before associates picked him up and drove him to Belgium.
Seven attackers died in the multi-venue assaults -- outside the stadium, at restaurants and at a concert hall -- either by blowing themselves up or being shot by police, authorities say. One of the attackers was Abdeslam's brother Brahim.
Police also believe Salah Abdeslam bought detonators in France before the attacks, the source close to the investigation told CNN late last month.
French intelligence services believe Abdeslam escaped to Syria
, a source close to the investigation and a counterterrorism source said last month.
Authorities: Man transferred money to ringleader's cousin
Also Friday, Belgian authorities said one of the two unidentified suspects transferred money to a now-dead female cousin of suspected Paris attacks ringleader Abdelhamid Abaaoud.
The man, using the false Samir Bouzid identification card at a Western Union outlet in the Brussels area, wired 750 euros ($816) to Hasna Ait Boulahcen on November 17, the Belgian prosecutor's office said. Both of the newly publicized suspects -- the men going by the names of Soufiane Kayal and Samir Bouzid -- were at the store from which the money was sent.
Abaaoud, Ait Boulahcen and an unidentified man died during a police raid on an apartment in the Paris suburb of Saint-Denis on November 18, the day after the money transfer. The unidentified man detonated a suicide bomb during that raid, authorities said.
After the raid, investigators learned that Abaaoud and the other man who died in the raid were planning a suicide attack on the Paris financial district of La Defense on November 18 or 19, according to Molins, the Paris prosecutor.
Authorities released color surveillance images of the men in the Brussels-area store from which the money was sent to Ait Boulahcen. They also released black-and-white images; it wasn't clear if those images were part of the false ID cards.
Meanwhile in Paris, the Cafe La Bonne Biere, where five people died on November 13, reopened Friday for the first time since the attacks, according to its Facebook page.