Sri Lanka's main elephant orphanage staged its biggest mass christening Sunday by naming 15 baby elephants born in captivity, an official said.

Thirteen babies born last year and two in 2010 were given names chosen from among thousands suggested by visitors to the Pinnawala orphanage, director Nihal Senaratne said.

"An astrologer looked at the time of birth of each elephant. He then decided on the first letter of each baby's name according to its horoscope," Senaratne told AFP when contacted by telephone.

"The lucky letters were published and visitors were asked to suggest names accordingly," he said, adding that Sunday's ceremony was the biggest ever at the facility since it opened in 1975.

Foreign visitors to the orphanage named two of the babies Trinky and Elvina, while the others were given popular Sinhalese names including Mangala (meaning ceremonial), Singithi (small) and Ahinsa (innocent).

The orphanage, in a coconut grove about 80 kilometres (50 miles) east of Colombo, is a major tourist attraction and large crowds were present for Sunday's ceremony.

Babies are fed gallons of milk in public and the entire herd is taken across a main road to a nearby river at bathtime in a ritual that has become hugely popular with visitors.

Formally established in 1975, the orphanage shelters 83 elephants, most of whom were abandoned or separated from their herds when they were babies. Many have also been born at the orphanage.

Elephants are considered sacred animals and a number of the babies born at Pinnawala have been gifted to Buddhist temples to be paraded during annual pageants.

Sri Lanka's elephant population remains healthy despite decades of fighting between government and rebel forces in the island's north-east, the first survey since the end of the bloody civil war showed last year.

The survey showed the country had 7,379 elephants living in the wild, despite fears that the population had dwindled to an estimated 5,350. The country boasted 12,000 elephants in 1900.

The survey carried out in August last year counted 1,107 baby elephants in the wild, officials said.

The 15 babies were named: Singithi, Ahinsa, Themiya, Wanamali, Trinky, Elvina, Nandi, Mangala, Annuththara, Jeevaka, Kadol, Isira, Bimuthi, Aithi and Gagana.