Prosecutors on Sunday applied for an arrest warrant for the niece of President Park Geun-hye's longtime friend Choi Soon-sil in a rich seam of the crony scandal that is gradually opening up.

Jang Si-ho, who was allegedly her aunt's closest aide, was detained for questioning Friday on suspicion of embezzling hundreds of millions of won from a W1.6 billion donation from Samsung to a youth winter sports foundation she established in June last year (US$1=W1,185).

She is accused of extorting the donation from Samsung in complicity with Kim Chong (55), a former vice culture minister who also faces arrest.