Brazil's leftist leader Luiz Inacio Lula da Silva, who was due to head to Beijing for key talks with President Xi Jinping, has indefinitely postponed his trip to recover from pneumonia, the Brazilian government said on Saturday.

Lula, who succeeded the far-right leader Jair Bolsonaro at the start of the year, had hoped to use the trip next week to reclaim his country's role in global diplomacy, with discussions expected to focus on reinforcing trade and the war in Ukraine.

No new date was given for the 77-year-old Lula's trip, the government said, adding that Chinese authorities had already been told of the decision.

Lula had originally been scheduled to leave on Saturday but that was put back by a day due to what his office called a case of "mild pneumonia," which was being treated with medication.

But doctors suggested he put the trip off after a new exam on Saturday.

"Despite the improvement in his condition, the president's medical service recommends that the China trip be postponed" until Lula is no longer contagious, physician Ana Helena Germoglio said, according to the government statement.

Just three months into his latest term as president – he has already visited Argentina and the United States – the six-day trip to China, Brazil's largest trading partner, was seen as key for Lula.

The official visit was set to begin on Tuesday with his meeting with Xi.

Lula's health has been a source of concern in recent years.

In November, Lula – who first governed Brazil from 2003 to 2010 – had surgery to remove a lesion from his vocal cords.

The president was diagnosed with throat cancer in 2011, shortly after he left the presidency. He went into remission after undergoing treatment. (AFP)