Parliament will debate the amendment on Wednesday and Thursday, and a vote on a rectified bill is scheduled for Thursday evening.
Fifteen of the arrests took place in Barcelona while another person was detained in the city of Girona, about 100 kilometres (60 miles) further north, police in the wealthy northeastern region said.
It said oligarchs with links to Russian President Vladimir Putin used their wealth for 'extending patronage and building influence across a wide sphere of the British establishment'.
Two years on from the referendum, the YouGov poll showed that the views of most voters on whether to leave had not changed.
Spain on Tuesday began to pull the police reinforcements it had sent to Catalonia ahead of a contested independence referendum in the region on October 1, the government said.
As Catalonia's independence crisis deepens, here are the key events that have rocked the region since this month's referendum on splitting from Spain.
Spain's premier urged senators Friday to adopt radical measures to impose direct rule on rebel Catalonia and depose its president in a bid to halt the region's independence bid.
The crisis was sparked by a divisive independence referendum that went ahead on October 1 despite a court ban.
Spain's Constitutional Court ruled Tuesday that a referendum law passed in Catalonia, which paved the way for a contested October 1 secession referendum, was not valid.
Catalonia's separatist leaders had on Tuesday signed an independence declaration but said they were suspending it in the hope Madrid would negotiate.
The Catalan president says he has a mandate to declare independence for the northeastern region, but proposes waiting "a few weeks" in order to facilitate a dialogue.
Even some of the most enthusiastic supporters of independence admit Catalonia is ill-prepared for total self-rule.
Catalan independence would not enjoy international recognition, France's minister for European affairs said as the Spanish region's leader threatens to announce a split.
Catalonia's leader has vowed to declare independence within days, claiming a mandate from Sunday's referendum which was declared illegal by Madrid and the Spanish courts.
The far-left party CUP says the Catalan government plans to present the results of last Sunday's disputed referendum on Monday, which will trigger a declaration of independence.