Jim Murphy has pledged to end the streak of "losing Labour" in Scotland as he launched his bid to become the next leader of the Scottish party.

The East Renfrewshire MP joins Lothian MSPs Neil Findlay and Sarah Boyack in the race to replace Johann Lamont, who resigned on Friday with an attack on UK Labour colleagues whom she accused of treating Scotland as a "branch office".

Mr Murphy has said he will stand for a seat in the Scottish Parliament in 2016, if not before, and is running with a view to becoming first minister.

The shadow international development secretary told BBC News he is confident he can turn around the party's fortunes in Scotland.

He said: "I'm not interested in left-wing Labour or right-wing Labour, or old Labour or new Labour. I'm interested in losing Labour.

"I want to end that period of losing Labour here in Scotland, starting with the UK general election in 2015, where I'm confident we can hold all the seats we currently have but pick up one or two on top and also win that election in 2016 for the Scottish Parliament."

Pledging to unite the party, Mr Murphy said: "There is so much that has to change about the Labour Party and so much that has to change about our country.

"I'm determined to bring the Labour Party together, end the period of self harm that we've had in the Scottish Labour Party and get on and improve our country."

He said he is "big enough and ugly enough" not to be pushed around if elected leader, but denied Ms Lamont's claim that the Scottish party has been treated like a branch office.

Mr Murphy said: "I don't think the Scottish Labour Party has ever been run in that way. The Scottish Labour Party takes so many of its own decisions but I want to do more of that. I want to devolve and have a more autonomous Scottish Labour Party.

"No one will tell me what to do if I'm Scottish Labour Party leader."

He added: "I'm confident that I can appeal not just to Scottish Labour voters, not just to trade unions, but to people who are undecided, people who turned away from us in recent elections in Scotland and build that movement for change here in Scotland

"These labels of left and right - I just want to unite the Labour Party, I want to bring the Labour Party together and bring Scotland together after the difficulty and passion we had in the referendum."

In another interview, Mr Murphy said: "I think it is time for a fresh start for the Scottish Labour Party. I am proud of the Labour Party and I am proud of Scotland - but I am not satisfied.

"I am not going to shout at or about the SNP, I am going to talk to and listen to Scotland and I am very clear that the job I am applying for is to be the first minister of Scotland."

Mr Murphy played a key role for Better Together during the referendum campaign when he carried out his pro-union 100 Streets in 100 Days tour.

Former prime minister Gordon Brown ruled himself out of the running in the leadership contest but Mr Murphy plans to meet him to discuss further devolution for the Scottish Parliament.

Mr Findlay, Scottish Labour's health spokesman, announced his intention to stand yesterday.

He said he wants to work for progressive change and "create a fairer, more equal and prosperous Scotland".

''I have been overwhelmed by the messages of support from people from within the Labour Party and across the wider Labour movement, all urging me to stand," Mr Findlay said.

''It is no secret that I wanted Gordon Brown to run but since Gordon has ruled himself out, I now believe we need to have a wide-ranging debate about the way forward for the Labour Party, but more importantly the country.

''If elected Labour leader, I will put the issue of social justice at the heart of everything we do - this is the historic mission of the Scottish Labour Party but it also has to be about what we deliver for the Scottish people in this post-referendum period.''

Ms Boyack co-chaired the review of Scottish Labour with Mr Murphy in 2011, which was designed to make the Scottish leader head of the entire party in Scotland, including MPs, MSPs, MEPs and officials.

She announced her intention to stand on Tuesday.

She said: ''Scottish Labour is going to be the key party in the run-up to the UK elections. It's absolutely crucial that we get an Ed Miliband government elected.

''So, that's why I believe in putting my name forward. I can work with colleagues and I can take that debate forward. That is the key thing.

''I did the review of the Labour Party just a couple of years ago. There's unfinished business there.

''But the key thing is what does the Labour Party stand for, how can we work together and how can we support people around the country?''

Mr Murphy announced that MSPs James Kelly and Jenny Marra will act as joint chairs of his leadership team.

He will formally launch his campaign this weekend under the slogan Leading Labour, Changing Scotland.

Commenting on how his move to Holyrood would work, the MP said: "I'm going to take it one election at a time, I'm going to see if I can win this contest and then of course the commitment would be to be a candidate for the Scottish Parliament elections in 2016 - and be a candidate for First Minister - if not earlier than that actually if an opportunity arose, but at the moment I'm concentrating on winning this.

"There are already two other really good candidates and it's going to be a fascinating contest.

"I'm really looking forward to it because Neil Findlay and Sarah Boyack are both friends of mine, we'll have disagreements but we'll come together at the end of this and unite the Scottish Labour Party and do that to try and change the country for the better."

Interim leader Anas Sarwar has said that he ''absolutely'' can carry on as deputy leader if another MP emerges to lead the party.

But Mr Murphy said: "I think if I'm elected leader it's likely, in fact I think it would be compulsory, that it would be an MSP that would be deputy leader.

"But on the basis that the other two candidates for leader are MSPs there may be an argument that says if one of them wins the deputy should be an MP.

"These are the things that will have to be resolved but I think it's important to have that kind of balance and have the Labour Party working together.

"I want the party to feel a sense of confidence in itself, have a passion about its politics and be as confident about Scotland as it can be."

He added: "I will lead Labour from Scotland, for Scotland. I will listen and work with everyone who wants to make this a fairer country, but I will never be afraid to speak my mind and to stand up for what is right for Scotland.

"I call on the millions of Scots who want to see Scottish Labour back in the fight to join me."