Nearly one-third of citizens in the Pacific nation of Tuvalu are seeking a landmark climate visa to live in Australia as rising seas threaten their palm-fringed shores, official figures show.

Australia is offering visas to 280 Tuvalu citizens each year under a climate migration deal Canberra has billed as "the first agreement of its kind anywhere in the world."

More than 3,000 Tuvaluans have already entered a ballot for the first batch of visas, according to official figures on the Australian program, almost a full third of the nation's population.