The number of asylum seekers on watch at Christmas Island detention centre has risen to 14.

Earlier this week nine asylum seeker mothers, who threatened suicide in a bid to have their Australian-born babies resettled here, were placed under 24-hour surveillance.

Since then, six more asylum seekers have been added to a watch list, Christmas Island shire councillor Gordon Thomson said.

There are 28 guards working 12-hour watch shifts.

A shortage of female guards meant some women were under watch from male officers, Mr Thomson said.

“Serious conflict will arise and eruptions have started because a male guard is supervising a woman nursing a baby and breastfeeding,” he told AAP on Thursday.

Serco, the company managing the detention centre, was trying to get around the problem by making male guards keep watch from outside rooms, but through an open door.

“It somewhat diminishes the effect of supervision,” Mr Thomson said.

Serco is flying in 55 extra staff on Friday, but it’s unclear how many of them are female.

Comment has been sought from Serco and Immigration Minister Scott Morrison.