A Metro Vancouver piano teacher who spent more than two decades giving private lessons to children in their homes is facing more sexual assault charges, court documents show.

Dmytro (Dmitri) Kubyshkin appeared in a Port Coquitlam courtroom Friday afternoon, and informed the provincial court judge he was pleading not guilty to all charges.

He's asked for a trial, which is expected to last between two and three weeks. No date has been set.

Initially charged with three assaults involving former students alleged to have occurred between 1998 and 2015, the list grew to nine counts of sex assault as more victims came forward.

He was also charged with two counts of sexual interference of a person under 16, two counts of interference with a person under 14, and two counts of invitation to sexual touching.

In total, he faces 15 charges.

Mounties have provided few details about any of the allegations, and said that he was not previously known to police.

He was most recently working under the company name DM Piano School.

With files from CTV Vancouver's Angela Jung