YANGON, April 2 (AFP) - Sandar Win, the favored daughter of former dictator Ne Win, is portrayed by Myanmar's military leaders and independent analysts as the brains behind what was once the nation's most powerful family.

A medical doctor aged in her 50s, she was reputed to preside over a clan that parlayed its patriarch's influence into a significant business empire encompassing hotels, medical services and telecommunications.

Their downfall last month, accused of plotting a coup against the current military regime, shocked observers in Yangon who had seen them as untouchable despite the waning influence of Ne Win as he moved into his nineties.

Since the arrest of her husband and three sons, in a raid on a restaurant where they were allegedly discussing the coup, Sandar Win and her father have been held at their sprawling lakeside residence, behind a heavy guard.

But on Tuesday the junta said that along with her husband and children she would face charges of high treason, which carry the death penalty.

"When the time comes for us to take Khin Sandar Win into custody, we'll do that without delay. We believe she is the key player in the scenario for the coup which has now backfired," a senior official said.

For many years Sandar Win served as a go-between linking her father with the generals in the current military regime, passing on requests for assistance and arranging meetings with the "Old Man", as he is known.

Sandar Win was known to be extremely ambitious and believed to have been attempting to carve out a high public profile for herself in what some said was part of a plan to become a future political leader.Reputed to be sharp but calm in character, she is the closest family member to Ne Win as the rest of the relatives are largely estranged.

There was even speculation that there might eventually be an all-female struggle for power in Myanmar, between Sandar Win and pro-democracy leader Aung San Suu Kyi who is herself now under house arrest in Yangon.

Since Ne Win's retirement in 1988, his protege Lieutenant-General Khin Nyunt, the powerful chief of military intelligence, had been seen as the family's guardian.But in recent times even he tired of their dodgy business dealings and outrageous behaviour.

Last year Khin Nyunt said he was "washing his hands" of one of the sons, Kyaw Ne Win, a notorious hooligan whose "Scorpion" gang roamed Yangon with impunity in black vehicles stripped of their licence plates.

In Yangon there have been few tears shed over the stunning moves against the Ne Win family. Sandar Win earned particular dislike for what many saw as a significant role in the bloody suppression of a 1998 uprising.

The military regime has not yet indicated what it will do about the complicated web of businesses built up by Sandar Win and her husband, although unconfirmed reports have said their accounts have been frozen.But the junta said the family's growing discontent over the lack of privileges being extended to them by the government had sparked the coup attempt.