Iranian President Mahmoud Ahmadinejad on Thursday published an offer for "any medical assistance" Brazil's former president Luiz Inacio Lula da Silva might need in his fight against throat cancer.

"While we are certain that Brazil is home to some of the best and most experienced doctors and specialists, I would like to hereby announce that my country is ready to offer any medical assistance that you may require," Ahmadinejad wrote in a letter made public on his presidential website.

The Iranian leader paid homage to 66-year-old Lula as "one of the most important politicians in Brazil... and among those who call for global peace and justice."

The offer underlined the ties built up between Ahmadinejad and Lula during the latter's 2003-2010 presidency.

Lula notably congratulated Ahmadinejad immediately after he was declared the victor of Iran's disputed 2009 elections, and defended Iran's controversial nuclear programme.

In 2010 he spearheaded talks along with Turkey to get Iran to agree to exchange low-enriched uranium for higher-enriched stock, but the deal foundered when the United States and its allies said it was insufficient.

He was being treated by the Sirio-Libanes Hospital in Sao Paulo, one of the most advanced medical facilities in Latin America. Doctors were hopeful of eliminating the cancer and seeing Lula resume normal activities within months.

Lula's successor, Dilma Rousseff, has cooled relations somewhat with Iran since taking office as Brazil's president in January this year.