Inter have been under pressure to raise funds because of their financial situation but had intended to hold on to Lukaku. His impending move means they plan to keep Lautaro Martínez, for whom Tottenham have offered €70m.
Lukaku is well acquainted with the Premier League having joined Chelsea from Anderlecht in 2011 and also played for West Brom, Everton and Manchester United. He turned down the chance to return to Stamford Bridge before eventually linking up with Antonio Conte at Inter last season.
But the Italian’s surprise departure at the end of May, not long after securing the club’s first Serie A title in 11 years because of disagreements over the transfer budget, opened the door for Lukaku to rejoin Chelsea.
It is understood Chelsea have also shown an interest in the Stuttgart striker Sasa Kalajdzic, although any move for the Austrian would depend on the departure of Tammy Abraham, who is wanted by Arsenal.