Smalling has played no part for England in the last two major international tournaments and was not called up for the recent Nations League games against Italy and Germany.
His last appearance for the Three Lions was back in 2017.
Smalling has slowly rebuilt his career in Italy with Roma over the last three seasons, having initially joined on loan from Manchester United in the summer of 2019.
The 32-year-old, who has 31 caps for England, helped Roma win the inaugural UEFA Europa League last season and has three goals in 10 Serie A appearances so far this term.
England manager Gareth Southgate has defensive headaches at the moment, with Reece James and Kyle Walker injured while Harry Maguire is out of favour at Manchester United.
Mourinho believes Smalling has done enough to merit a spot in the England squad for the World Cup.
‘He was taught to play in a two-man defence in Manchester, but now he’s got the perfect acumen to play in a three-man backline,’ Mourinho said.
‘If I were the coach of a national team, I would do anything to have someone like him at my disposal.
‘I don’t think it’s a lack of respect to Gareth Southgate when I say that I feel very sorry for a player who’s playing at such a high level like Smalling and who won’t get the opportunity he deserves.’
Smalling's tournament experiences for England came at the 2014 World Cup and Euro 2016.
