Peter Law is to stand in Blaenau Gwent

Mr Law, who has left Labour, said he will campaign in protest at the party leadership's decision to impose an all- women shortlist on the constituency.

He originally dropped plans to fight the seat just two weeks ago because of a brain tumour and underwent surgery.

But on Monday, he confirmed he would contest Wales' safest seat after all.

The Blaenau Gwent AM initially threatened to stand 18 months ago if Labour used an all-women shortlist to choose a successor to the retiring MP, Llew Smith.

Mr Law told BBC Wales on Tuesday he had recovered well from surgery and had begun to campaign.

'Walked over'

He added: "I'll be in Blaina this morning and in Ebbw Vale. I've already been to Abertillery and Brynmawr - I'll be out there working with the people.

"I think it (all-women shortlists) has become such an issue over the last two years that people became deeply offended they were treated in this way - they're not here to be walked over.

"If I can facilitate a choice for the people then I'm pleased to be doing that because their faith and support in me has been so vitally important."

Maggie Jones was chosen for Labour from an all-women list

Mr Law's decision posed two immediate problems for Labour. It will have to defend a seat regarded as rock solid, and it has now also lost its working majority in the assembly.

Mr Law also confirmed on Friday that he had left Labour, which had held 30 of the 60 assembly seats. Although he will still be an AM, he is now an independent.

Even if he had not left, under party rules he is considered to have expelled himself by announcing he would stand against a Labour candidate.

The selection of Maggie Jones, a union official with Unison, led to the resignations of most of the Blaenau Gwent party executive.

'Protest vote'

Labour argues that there are too few women in parliament, and special measures are needed to redress the balance.

Maggie Jones told BBC Wales on Tuesday: "We regret Peter's decision to leave the party and stand in this way, but there are bigger issues here.

"What the general election is about is choosing the next government. It's not a single issue campaign, it's about (Labour) standing on our record.

Blaenau Gwent is the safest seat in Wales

"There will always be a small amount of people who wish to exercise a protest vote. I don't intend to make this a personal battle - if anything it's other people attempting to make it personal about me."

Plaid Cymru candidate John Price said: "Peter is fighting this seat because he is annoyed with the way Labour has imposed Maggie Jones on the people of Blaenau Gwent as their candidate.

"Plaid are not going to get involved in the mudslinging that is will probably go on between Peter and Maggie Jones.

"We prefer to concentrate on telling the people of Blaenau Gwent what we intend and can do (for them)."

Conservative candidate Phillip Lee added: "If Peter wasn't standing, the media would expect it to be a shoo-in.

"In fact, I suspect that Mr Blair thought Blaenau Gwent was in the bag - now he knows it's not.

"It gives me the opportunity to talk about Conservative policies of more police (and) lower council tax."

Liberal Democrat candidate Brian Thomas said he was pleased Mr Law was standing and the seat was a three-way fight between Mr Law, Labour and the Lib Dems.

"It is a possibility if Peter Law and Maggie Jones fight amongst themselves then I could possibly sneak in there and become the Member of Parliament for Blaenau Gwent," Mr Thomas said.

On 3 April, the day before Mr Law was originally set to announce his candidacy, he discovered he had a brain tumour.

He initially dropped his plans to contest the seat, and underwent surgery later that week.

Labour is defending a 19,313 majority in the seat, which has been held by the NHS' founding father, Aneurin Bevan, and former Labour leader Michael Foot.