The trial of three men over their alleged roles in the 2017 jihadist attacks in Barcelona and a nearby town that killed 16 people was suspended Thursday because a defence lawyer has the coronavirus.

The trial, which opened in November in San Fernando de Henares near Madrid, will resume once the lawyer and another defence attorney with a suspected case of COVID-19 recover, presiding judge Alfonso Guevera told the court.

Over 200 witnesses have already taken the stand, including police, victims and neighbours of the defendants, and the prosecution has already made its final arguments.

All that remains is for the defence lawyers to make their closing arguments.

Prosecutors are asking for prison terms for the three men ranging from eight to 41 years.

They are not accused of taking part directly in the attacks, which were claimed by the Islamic state group, but of belonging to the extremist cell that carried them out.

On August 17, 2017, a man driving a van ploughed into people on Barcelona's crowded Las Ramblas boulevard, killing 14 before escaping on foot.

The driver went on to kill another person before being shot dead several days later.

The next morning, five other members of the same cell drove into pedestrians in Cambrils, a resort 100 kilometres to the south, and fatally stabbed a woman before being shot dead by police.

The three defendants have denied being part of an extremist cell.