WARSAW, Poland– The parents of late Russian opposition leader Alexei Navalny thanked the crowds of Russians paying their respects to their son in a message published Saturday by his widow Yulia Navalnaya.

Navalny -- President Vladimir Putin's main opponent -- died in his Arctic prison in mid-February and was laid to rest in Moscow last week, with streams of Russians bringing flowers to his grave since despite the threat of arrest.

"A huge gratitude and low bow to those who came and come to the cemetery, who bring flowers, write about Alexei, remember our son, pray about him!", the politician's parents, Lyudmila and Anatoly, said in a handwritten note.

"Thank you for the memory! The memory which gives hope!", they added.

The couple thanked Russians who "with us feel the pain of loss."

Navalny's mother Lyudmila had spent more than a week trying to retrieve her son's body, before officials finally allowed her to bring him back to his native Moscow.

He was buried in Moscow's Borisovo cemetery amid thousands of mourners.

People have continued to bring flowers to Navalny's grave after his funeral.

Yulia Navalnaya has vowed to continue her husband's work and called on Russians to stage protests by forming long queues outside voting stations in Russia's upcoming presidential elections.