Indian surgeons who removed a massive brain tumor in a marathon seven-hour procedure said Thursday they believe it could be the heaviest ever recorded.

Neurosurgeon Trimurti Nadkarni told AFP the operation took seven hours to complete and the patient required 11 units of blood.

Santlal Pal, a 31-year-old shopkeeper, had been carrying around a tumor weighing nearly two kilos before the surgery on Feb. 14.

"It was an extremely daunting and complex surgery," said Nadkarni, head of neurosurgery at Mumbai's BYL Nair hospital.

"After the patient regained consciousness, we researched and concluded this was the world's heaviest tumor to be reported so far."

The 1.87-kilo (four-pound) brain tumor had affected his vision and caused constant headaches.

"It was a rare operation and the patient has survived. Before the surgery, he had minimal vision, which may improve now," Nadkarni said.