She was speaking after thousands of people took to the streets of Barcelona on Wednesday after police detained key members of the team organising an outlawed independence referendum for Catalonia set for October 1st.
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"It is of course entirely legitimate for Spain to oppose independence for Catalonia, but what I think is of concern anywhere is for a state to seek to deny the right of a people to democratically express their will," Sturgeon told lawmakers.
"The right of self-determination is an important international principle, and I hope very much that it will be respected in Catalonia and everywhere else."
Sturgeon, the leader of the pro-independence Scottish National Party, also called for dialogue between the Catalan and the Spanish governments to try to resolve the situation.
"That has got to be preferable to the sight of police officers seizing ballot papers and entering newspaper offices."
The SNP secured a referendum on Scottish independence from the rest of Britain in 2014, but voters rejected their call by 55 percent to 45 percent.
After Britain voted for Brexit last year, Sturgeon raised the possibility of another referendum for Scotland, although she has since pulled back from the idea.