Image copyright PA Image caption Kenny MacAskill was justice secretary for more than seven years

Former justice secretary Kenny MacAskill is to stand down as an MSP at next year's Holyrood election.

The SNP member for Edinburgh Eastern said he wanted to "pursue new challenges", but said he would remain committed to the independence campaign.

Mr MacAskill, 57, was justice secretary for seven-and-a-half years.

Opposition parties were critical of a number of his decisions during his time in office, including plans to abolish corroboration which were later dropped.

Mr MacAskill was succeeded by Michael Matheson in First Minister Nicola Sturgeon's new administration.

The first minister tweeted that Mr MacAskill had made an "outstanding contribution to Scottish politics over many years" and would be a big loss to the Scottish Parliament.

'Proud' record

During his time in the role he also made the controversial decision to release Abdelbaset al-Megrahi, the only person convicted of the 1988 Lockerbie bombing, on compassionate grounds.

Mr MacAskill wrote to constituency members last night to tell them of his decision to step down in May 2016.

Speaking to the The National newspaper, the former solicitor said: "I'm proud of the commitment and efforts I made, but it will now be up to others to take things forward.

"I am not leaving parliament to retire, but am leaving to pursue what might be considered a third career.

"Independence for Scotland will remain dear to my heart and I will be committed to it."

'Heavy heart'

Mr MacAskill was elected a Lothians list MSP in 1999 and 2003, before winning the Edinburgh East and Musselburgh seat from Labour at the 2007 election.

In 2011, he was elected MSP for the newly named constituency of Edinburgh Eastern.

Regarded as one of the SNP administration's heavyweights, he served as justice secretary from 2007 to November last year.

An excerpt from his letter to constituents, published in The National, said: "It is with a heavy heart that I have decided that it is time both for someone new and something new."

Mr MacAskill said he had always planned to stand down in 2016, even if Scotland had returned a Yes vote in September's independence referendum.