The Government is planning to introduce measures to limit any cut in the size of the Northern Ireland Assembly.
Under legislation currently going through Parliament, the Assembly, with the approval of the Northern Ireland Secretary, could cut the number of its members.
But following concerns raised by peers, Northern Ireland spokeswoman Baroness Randerson said she would bring forward changes to the planned new laws to ensure the Assembly would not become too small.
At present there are 108 MLAs, with six elected in each of the 18 parliamentary constituencies.
Under the new proposals, only one seat per constituency could be cut, meaning the Assembly would retain at least 90 members.
Peers including former Ulster Unionist leader Lord Empey and former Assembly speaker Lord Alderdice argued at earlier stages of the Northern Ireland (Miscellaneous Provisions) Bill that a significant cut could affect smaller parties.
Lady Randerson told peers at report stage: “In their view the Secretary of State’s ability to withhold consent from such an arrangement was not a sufficient safeguard.
“The Government recognises those concerns. There is a significant body of opinion that favours some reduction in the Assembly size but it is certainly not our intention that it should become a radically smaller institution.
“When it was established it was the intention it should be a widely inclusive body and that remains an essential element of the Northern Ireland settlement.”
She said the Government would bring in an amendment at third reading to limit any reduction in the Assembly size to five members per constituency.
“The amendment would make clear that such a reduction would require cross-community support,” she added.
Later, Tory Lord Lexden called for the “benefits” of new libel laws under last year’s Defamation Act to be extended to Northern Ireland.
Lord Lexden said there was “practically universal agreement that the new law strikes the right balance between protecting individual reputations and upholding freedom of expression”.
He said the benefits will be enjoyed in England and Wales but not in Northern Ireland.