Image copyright PA Image caption Keith Brown has announced his intention to stand as deputy leader of the SNP

Keith Brown and Stewart Hosie have formally put their names forward as candidates for the deputy leadership of the SNP.

Mr Brown, the current transport secretary, announced his candidacy at an event in Edinburgh.

Dundee East MP Stewart Hosie also announced he is seeking the role.

It is currently held by Nicola Sturgeon, who intends to succeed Alex Salmond as SNP leader and Scottish first minister.

Mr Brown, the MSP for Clackmannanshire and Dunblane, said his goal was to help the SNP achieve its two founding aims: Scottish independence, and to "further the interests of the people of Scotland".

Mr Brown, a former Royal Marine, added: "Those interests must include the maximisation of the powers we need to address the pressing needs of the people of Scotland: for jobs, for greater equality and life chances, and the social justice that, as in the 1980s, has been so undermined by the austerity agenda."

Image caption Stewart Hosie is currently the SNP's Treasury spokesman at Westminster

He also pledged to help ensure the three main Westminster parties keep their pre-referendum vow of delivering greater powers to the Scottish Parliament.

On the prospect of another referendum, he said: "Any further attempt to ask the people to support independence has to be through the ballot box and through a referendum."

But he added that "in terms of putting a time limit, you can't do that, it really does depend on circumstances and the people".

Mr Hosie, the SNP's Treasury spokesman at Westminster, said he wanted to keep the "Yes" movement together to maximise the extra powers that come to Holyrood.

Analysis: Andrew Black, BBC Scotland political reporter

And so we now have a competition for one of the top jobs in the SNP, that of the party's new deputy leader with two candidates - one MSP and one MP - throwing their hats into the ring.

Both say their priority is ensuring Scotland gets as many new powers as possible following the independence referendum "No" vote, although each is approaching the argument from a different geographical perspective.

Former Royal Marine (and current transport minister) Keith Brown is up for the fight to succeed Nicola Sturgeon as deputy leader, with his pledge to ensure new Scottish Parliament powers are used in full.

Had Scotland voted for independence, Scottish MPs like Stewart Hosie would have been looking for a new job. As things have worked out, the SNP Treasury spokesman now has an eye on next year's Westminster poll.

He wants to ensure the SNP wins as many Westminster seats as possible in 2015, to send a strong message that Scotland is serious about gaining new devolved powers.

Mr Hosie further argues his and Ms Sturgeon's election as the SNP's new leadership team by party members provides a balance of "east/west, man/woman, and Holyrood/Westminster" at a time when the independence movement has attracted diverse support.

It's also worth remembering that whoever becomes SNP leader and first minister (the only current candidate being Ms Sturgeon) is expected to name a deputy first minister.

If an MSP (like Mr Brown) becomes deputy leader, it's likely to be him. If the job goes to an MP (like Mr Hosie), the new SNP leader (like Ms Sturgeon) could name her own deputy FM at Holyrood.

Finance Secretary John Swinney (who ruled himself out of any party leadership role) has been tipped for such a position.

But he said it was important for the SNP to also reach out to the 55% of voters who rejected independence in last week's referendum.

Speaking in Dundee, he said: "It will be vital to keep the energy of the 'Yes' movement alive as we continue to campaign for more powers. The next opportunity we have to do that is the 2015 General Election.

"But let me be clear - I do not believe that election should be a re-run of the referendum.

"Rather it is Scotland's chance to hold Westminster to account - to hold their 'feet to the fire' - ensuring that they keep their promise to deliver devo-max - maximum devolution - and that means devolving everything apart from defence and foreign affairs."

In the six days since the referendum ended with voters rejecting independence, the SNP membership has been swollen by "Yes" campaigners, rising from about 25,000 to more than 60,000.

Its membership is the largest for a political party in Scotland and the third largest in the UK, having overtaken the figure for the Liberal Democrats UK-wide earlier this week.

Confirming her leadership bid for the party leadership on Wednesday, Ms Sturgeon said the country could only become independent if the electorate backed the move in a referendum.

Media playback is unsupported on your device Media caption Nicola Sturgeon: "My task will be to lead Scotland into an exciting new chapter in our national story."

But she did not rule out the possibility of the SNP including a commitment to hold a second referendum in a future election manifesto.

As SNP leader Ms Sturgeon would also become Scotland's first minister, the first women to hold the post.

She said: "To be the first minister of my country, especially at this exciting and optimistic time, would be both a great honour - without doubt, the greatest honour - and an immense responsibility.

"I am putting myself forward for two simple reasons: I want to serve my party and my country. And I believe I am the best person for the job.

"I also hope that my candidacy, should it succeed, will send a strong message to every girl and young woman in Scotland - no matter your background or what you want to achieve in life, in Scotland in 2014 there is no glass ceiling on ambition."

Nominations for both leader and deputy leader remain open for three weeks. The winners will be decided by a ballot of all party members, with the results being announced at the party conference in November.