Downing Street was accused of conducting "shabby" politics by Labour after David Cameron and Nick Clegg took a new anti-sleaze bill, announced in response to the lobbying scandal, and inserted last-minute plans to clamp down on union funding of election campaigns.

The surprise move was designed to reduce the impact of union support for Labour in the runup to an election, and came as Clegg said he would introduce a bill to create a statutory register of lobbyists in time for this summer's parliamentary recess.

Cameron and Clegg agreed to incorporate the union funding measures at a bilateral meeting in the morning. No 10 then announced them in the afternoon, in moves that even seemed to catch some junior members of the government off guard.

In a further development on Monday night, the Speaker, John Bercow, suspended 80 passes to the House of Commons pending investigations into all-party parliamentary groups by the Commons standards committee.

The Speaker instigated an inquiry into the groups last year, which has now been given new urgency after the lobbying revelations in recent days.

The new anti-sleaze bill will include measures to control in the year prior to an election any spending of third-party organisations affiliated to parties and any organisation contributing £100,000 or more. In practice, this only applies to the trade union funding of Labour and will exclude figures such as the former Conservative deputy chairman Lord Ashcroft, who has funded individual Conservative associations.

A Labour spokesman said: "The best way to proceed if you want to take big money out of politics and clean up the lobbying scandal is to act on a cross-party basis. Labour has done so.

"This seems to be a shabby and panicked response by Cameron to divert attention from a set of damaging headlines hitting the Conservative party".

No 10 said that in future the full costs of any third-party election campaign expenditure, rather than just marginal costs, would be counted towards a party's spending cap at national and constituency level. In the case of leaflet printing, full costs include an allocation for staff and premises while the marginal costs only count paper and ink.

Jack Straw, the former Labour cabinet member once responsible for inter-party talks on party political funding, said he was surprised that the coalition had immediately jeopardised chances of cross-party agreement with its unilateral move.

He said: "There was a good chance of party consensus on these matters, but the government has thrown a firecracker into this proposal by including a totally extraneous matter of trade unions that should have been dealt with separately."

The prime minister's spokesman confirmed there had been no public consultation on either measure, or any previous suggestion that the measures should be included in a bill clamping down on lobbying. Neither measure was included in the coalition's programme or the government's midterm review.

In a sign of the sudden birth of the plans, the Liberal Democrat deputy leader of the house, Tom Brake – who is nominally in charge of the lobbying legislation for his party – seemed unaware of the plans to tack on union funding issues, saying the proposal sounded premature. An hour after Downing Street briefed on the plans Brake told BBC Radio 4: "The work I have been involved with has been very focused very much on lobbying and is a well developed proposal which the government expects to come forward with soon."

Later, the Lib Dems defended the goal of regulating those that seek to influence the democratic process, but a spokesman for the party added: "The issues are still being discussed in government, and details have yet to be agreed. The aim of any reform in this area must be to make the political and democratic process more transparent, accountable and properly regulated."

Downing Street also announced that it intended to end the self-certification of union membership lists, saying in future the existing certification officer would be empowered to mount investigations of membership lists, rather than wait for a third-party complaints.

In addition, unions will have to report annually to the certification officer on the accuracy of their membership lists.

Downing Street justified the move by saying there had been a series of trade disputes, most recently involving Unite and British Airways, in which it was clear unions had balloted individuals that were either dead or no longer union members.

Frances O'Grady, the TUC general secretary, said: "The government is cynically trying to exploit a political sleaze scandal to crack down on unions – which are democratic and accountable organisations. We already have some of the most restrictive union laws in all of Europe and this move smacks of naked opportunism."

The committee on standards in public life, on behalf of the government in November 2011, proposed lower individual donation caps, of £10,000 per year and a reduction in the current permitted campaign spending cap of £18m in the year before polling day.

The decision to suspend passes was made at a meeting of the all-party Speaker's commission. The focus was on the 45 or so passes given to those who work as or provide the secretariat to all-party parliamentary groups. A specific parliamentary pass for exists for these officials.

The Speaker's committee, with full Labour support, has also agreed to ask the standards committee to expedite its current, outstanding review into All Parliamentary groups. It is understood the Speaker is frustrated at the slow progress of reforms and feels some MPs have been showing a lack of urgency about the issue He has been pressing the issue for nearly two years.

The three peers caught up in a lobbying scandal are to be investigated by the House of Lords standards commissioner, it was announced on Monday.

Lord Hill of Oareford, the leader of the Lords, said the ex-cabinet minister Lord Cunningham and Lord Mackenzie of Framwellgate – who have both been suspended by Labour – and Lord Laird, who has resigned from the UUP, would all be subject to an inquiry.

Hill told peers: "The allegations made at the weekend are very serious and distressing to us all. I know I speak for all the parties when I say they do not reflect the house we know and the members who work here from a sense of public service, a desire to hold the government to account and to revise legislation," he said.

On Friday, Patrick Mercer, a Tory MP, resigned the whip after a BBC Panorama investigation showed him accepting money from people he believed were lobbyists, then tabling parliamentary questions they requested.

But the Cabinet Officer minister Francis Maude queried the effectiveness of the proposed statutory register of lobbyists. "The statutory register of lobbyists would have made no difference in this case at all because what's alleged to have happened would have been against the rules, parliamentary rules, in any event."