The woman was among scores of Rohingya families forced to take to the water as sections of the township of Kyaukpyu were set ablaze, the source said.
''Now there are still many boats on the water,'' the informant said. ''They cannot go back but they are suffering badly because they have no food and water.''
The account provided by the source, who says he has been in touch with people in the boats via mobile telephone, cannot be confirmed independently.
News media and aid organisations remain banned in the areas of Burma where renewed violence is reported to have claimed at least 60 lives as mobs burned out unwanted Rohingya Muslims this week.
The violence and continued protests aimed at driving out Rohingya from villages and townships are seen as an unofficially sanctioned ethnic cleansing process.
Satellite photography obtained by New York-based Human Rights Watch plainly shows that hundreds of Rohingya homes and houseboats have vanished in Kyaukpyu, about 200 kilometres south of the Rakhine state capital of Sittwe.
Unverifiable reports of massacres in boats as Rohingya fled reached Phuketwan yesterday from one of two sources with telephone connections to people in Kyaukpyu.
Today, with an unknown number of men, women and children said to be in boats sailing north in the hope of finding refuge in displaced persons camps around Sittwe, the mobile telephone batteries were running low.
Sailing north from Kyaukpyu to Sittwe without food and water could leave the young and the old at particular risk, if the reports are true.
About five townships and villages are said to have been subjected to violence this week in the first renewal of community clashes in Rakhine, also known as Arakan, where 90 people were killed in June.
The Rohingya, who claim to have lived in Burma for centuries, are stateless and deprived of human rights by the government and other locals who have been encouraged to force them to leave.
Human Rights Watch reported yesterday that violence continued all week in at least five centres: Kyaukpyu, Minbya, Mrak-U, Myebon, and Rathedaung.
However, Phuketwan's two sources said today that the fighting and mob violence appeared to have eased.
The issue, they said, was now about whether food, water and other aid was reaching the basic open refuges around Sittwe and the people now struggling to reach there in open boats.
More Rohingya than in previous years are expected to take to the Andaman Sea to sail south seeking sanctuary between November and April. In the past, many boats have come ashore in Thailand, north and south of Phuket, and on the holiday island.