"Speaking of the European Union's perspective on Ukraine's EU accession, my being here on the first day of the six-month presidency... demonstrates a clear and unequivocal political commitment on the part of the community institutions in this respect," he said in a joint news conference with Ukrainian President Volodymyr Zelensky.
Ukraine applied for EU membership just five days after Russia's invasion on February 24, 2022, and received candidacy status several months later on June 23 in a strong signal of support from Brussels.
It is hoping to begin formal negotiations this year on what it needs to do to firm up its membership bid.
Sanchez said the European Commission had recently issued an interim update on the status of Ukraine's candidacy which showed "significant progress" in implementing the recommendations ahead of membership talks.
"I would like to congratulate Ukraine for the positive trend and encourage it to continue its path of reforms," he said, indicating that a written report would be released in the autumn which would outline "the basis for further steps and decisions".
In an earlier address to Ukraine's parliament, the Spanish leader thanked lawmakers for their legislative work, recalling that Ukraine's desire to join the 27-nation bloc was one of the reasons for Russia's invasion.
"We do not forget that the European aspirations of the Ukrainian people was one of the excuses that triggered the Russian reaction, and in turn, the invasion. It was only fair to honour this aspiration by granting you the status of candidate to the European Union," he said.
"However, I know that this is not an easy process, especially with an ongoing war."
