Adams 'must follow parliamentary rules to resign as MP'
The Office of the Speaker of the House of Commons has indicated it still regards Gerry Adams as MP for West Belfast.
Sinn Fein has said Mr Adams, who is standing in the upcoming Irish election, resigned his West Belfast seat in a letter to the speaker.
However, the speaker's office suggested he had not complied with procedure.
A spokesperson said she undersood that he would remain an MP until parliamentary rules were followed.
Under procedures dating back to 1642, MPs are forbidden from formally resigning their seats.
They must apply for a position of profit under the crown, which automatically disqualifies them from being a member of the House of Commons.
Under those rules, Mr Adams has to apply to the Chancellor of the Exchequer to become Crown Steward and Bailiff of the Manor of Northstead.
The other office is Crown Steward and Bailiff of the Chiltern Hundreds, a role currently unavailable as it is held by former Strangford MP Iris Robinson.
A spokesman for the Treasury said that no application had been received by the Chancellor.
The Disqualifications Act 2000 means that Mr Adams could sit in both the House of Commons and the Irish parliament, the Dail.
A spokesperson for the Irish government said the law there permitted Mr Adams to sit in Dublin and London.
However, Mr Adams himself has said that he does not want to represent both constituencies.
When announcing his plan to run in the Louth constituency in November he said that he would "work and stay here and travel home when possible."
The rules, available on parliament's website, suggest that the problem cannot be solved by appointing Mr Adams to the role, regardless of his own wishes.
They state that an MP wishing to retire must apply themselves to the Chancellor of the Exchequer.
A Sinn Fein spokesperson has told the BBC that Mr Adams has no intention of doing so.
He said: It's a non-issue from our perspective. He submitted his resignation and that's it.
"He's stepped down from that position. He certainly didn't apply for the Stewardship of the Manor of Northstead."
BBC Newsnight political editor Michael Crick has blogged that Mr Adams' refusal to swear an oath of allegiance to the Queen could solve the problem.
He said that if Mr Adams tried to take his seat without taking the oath, he would be automatically disqualified.
A spokesperson for the NI Electoral Office has confirmed that it has not yet received a writ from parliamentary authorities, which is necessary to begin by-election proceedings.