President Azali Assoumani secured a second consecutive term in March, but critics alleged vote rigging and witnesses said ballot boxes were stuffed, the latest scandal in a country blighted by instability and coups.
The four main opposition parties said in a statement in October they would not take part in the 2020 parliamentary election unless they received guarantees it would be “transparent, free and democratic”.
But Azali told France 24 television on Wednesday: “My most ardent wish is that they come to participate in these elections because we have a lot to do.”
He rejected electoral fraud allegations, saying the March ballot had gone very well.
Among the opposition’s demands in the former French colony is that the country’s diaspora of roughly 300,000 — almost half of the island-nation’s resident population — is allowed to take part.
However, Azali’s allies have already said it would be practically impossible to organise diaspora votes by next year.
Azali initially came to power in a 1999 coup and ruled until 2006, before being re-elected in 2016.
He oversaw a referendum last year — boycotted by the opposition — that approved extending the presidential mandate from one five-year term to two, raising fears he intends to rule until 2029.
Comoros is one of the world’s poorest countries.
Azali has placed income from oil at the centre of his plans to make the country an “emerging economy” by 2030.