The 25-year-old suffered a heavy fall in a challenge with Real Madrid defender Sergio Ramos while playing for Liverpool in the Champions League final against Real Madrid on Saturday.
He left the field in tears amid serious doubts about his chances of playing for Egypt at their first World Cup since 1990.
But the Egyptian FA was more optimistic after Salah met the national team doctor in Spain.
"The (Egyptian) football association confirms once again ... Salah will be in the World Cup, God willing, and won't be absent for more than three weeks," it said on Twitter without giving further details.
Egypt begin their World Cup campaign against Uruguay on June 15, before facing hosts Russia on June 19 and Saudi Arabia on June 25.
On Sunday, Salah posted a message saying: "It was a very tough night, but I'm a fighter. Despite the odds, I'm confident that I'll be in Russia to make you all proud. Your love and support will give me the strength I need."
Egypt reached the tournament after Salah scored a 95th- minute penalty to help them beat Congo 2-1 in October.
Earlier on Wednesday, Liverpool physiotherapist Ruben Pons was quoted by the Spanish sports paper Marca as saying that Salah would be out for up to four weeks.
"He is sad about what happened but is totally focused on recovery, seeing when he can be ready," he said.
"In principle it will be between three and four weeks but we will try to reduce those dates, that's the big goal," Pons added.
Salah, who scored 44 goals in a sensational first season for Liverpool after joining from AS Roma, was voted Player of the Year by the Football Writers' Association this month, completing a sweep of England's individual prizes and becoming the first African player to win the prestigious award.
(Reporting by Rik Sharma in Madrid and John Davison in Cairo; writing by Brian Homewood; Editing by Ed Osmond)
