Eriksen, who joined Spurs from Ajax over the summer, was taken off during Denmark's 2-1 win over Norway on Friday.
He was later seen leaving the stadium on crutches, and Danish boss Morten Olsen confirmed that the Tottenham playmaker had suffered an ankle ligament injury which could keep him out for up to two months.
However the Daily Mail report that his injury may be even worse than initially feared and he is facing up to three months out of the game.
The paper adds that Spurs could receive compensation from the Danish FA if Eriksen is out of action for more than a month, which looks likely.
The news, if true, will come as a huge blow to Tottenham as they stare down the barrel of a tough run of fixtures in the Premier League.
They travel to Manchester City at the weekend before playing hosts to Manchester United seven days later, with a Europa League trip to Tromso in between.
Spurs would also have been relying on Eriksen to help them put an end to their goal drought; the north London club have managed just nine goals in 11 Premier League matches so far.
They currently sit in 7th in the league table, five points behind leaders Arsenal.