The Black Watch is being deployed to Iraq at the end of the year, the Ministry of Defence has confirmed.
The Black Watch has undertaken previous tours in Iraq
It will be the third time soldiers from the third battalion of the Royal Regiment of Scotland have been sent to Iraq since Saddam Hussein was toppled.
Just two weeks ago the Army denied that the Belfast-based Black Watch was being deployed there.
Scots Territorial Army reservists are also being deployed, defence officials said.
They will be sent as part of 19 Light Brigade, with a company from the 51st Highland, the 7th Battalion being sent in November.
The decision to send the third battalion, now based in Northern Ireland, was criticised by the Scottish Nationalist MP Pete Wishart.
Mr Wishart, whose Perth and North Perthshire constituency is part of the Black Watch's historical recruiting ground, said: "While I have absolutely no doubt that the Black Watch will perform their mission with their customary professionalism, it is simply not fair or right to put them back in Iraq for a third time.
"No other battalion or regiment has been asked to do so much in this conflict and the Black Watch have paid heavily for this over reliance."
The Black Watch has played a vital part in several conflicts in recent years.
In 2001 it completed a successful peacekeeping tour in Kosovo and was deployed in 2003 to Kuwait, before taking part in the invasion of Iraq and support operations around Basra.
The battalion moved back to the UK from Germany and was deployed to Iraq again in the summer of 2004.