The police station duty scheme began in July, after Holyrood passed emergency laws in October 2010 setting out new measures for the rights of suspects to legal representation.
The legislation was brought forward after the UK Supreme Court ruled that the Scottish system of allowing people to be held for six hours without access to a lawyer breached the European Convention on Human Rights.
Justice secretary Kenny MacAskill said the scheme, operated by the Scottish Legal Aid Board, now included a high level of participation from law firms, with 565 private solicitors taking part.
It also includes a 24-hour solicitor contact line manned by board-employed solicitors, which has helped to provide earlier and greater advice to suspects than was previously the case.
Speaking during a visit to the Scottish Legal Aid Board’s headquarters in Edinburgh, Mr MacAskill said: “The police station duty scheme has now been operating successfully for six months, and I am encouraged to see private practice solicitor numbers increase week on week, and is now approaching 600.
“I am grateful to all those solicitors for providing this important service, especially over the festive period.”
He added: “It is clear the scheme is working well, and in delivering access to legal advice for those in police custody, it is doing what it should do.”
Mr MacAskill was also shown a video conference pilot which links Northern Constabulary’s Stornoway police station interview room with the board’s solicitor contact line, reducing the need for solicitors to travel.