The deaths of four more asylum seekers at sea is a tragedy, but not a surprise, for a senior official at the heart of Australia's border control response.

A boat capsized about 7pm (AEST) on Tuesday while under the escort of two naval vessels en route to Christmas Island. Four bodies were recovered from the water and another 144 people were rescued.

"At one level, tragically, some of us weren't necessarily particularly surprised that another boat had capsized," Christmas Island administrator Jon Stanhope told ABC Radio on Wednesday.

The latest deaths come after the weekend drowning of a baby boy, who was on a vessel swamped by high seas as it struggled toward the Australian coastline.

"We now have mortuary facilities that will cater for 50 bodies and that is a statement within itself," Mr Stanhope said, adding that had increased from about five in the past year.

An average 100 people per day arrive at Christmas Island for refugee processing and three naval vessels based at the station were "constantly being called out".

As the perils of sea continue to prove deadly, Mr Stanhope said he would like to see a greater level of humanity shown towards boat people.

"I sometimes wish that among some of the debate and some of the commentary and some of the discourse, that each of us would look at asylum seekers not as a bulk, an anonymous grouping, but as individual human beings that have hopes and aspirations and dreams and feel the same pain and suffer the same grief as each of us," he said.