Police funding rules should be changed to allow Scotland Yard to claim back costs linked to terror attacks or the Grenfell Tower fire, a new report suggests.
A London Assembly committee called on the Home Office to adjust its guidance on "special grant" allocations for unexpected events.
The Metropolitan Police has launched major inquiries into four terror attacks and the Grenfell disaster this year.
A report from the London Assembly budget and performance committee cited suggestions the London Bridge attack alone will cost the force more than £10 million in extra resources, although this figure has not been publicly confirmed.
The report said: "The Home Office's current guidance expects the Met to hold contingencies for unexpected incidents such as London Bridge or Grenfell.
"We think that this is an unreasonable position and call on the Home Office to change the special grant guidance."
The allocation of special grant funding will only be considered for costs that reach 1% of a force's budget, unless the requirement is waived.
In effect, the size of the Met's budget, which is more than £3.2 billion for 2017/18, means it cannot apply for police special grant funding, according to the committee's report.
The assessment also warns the force faces a financial "black hole" of £185 million over the next four years.
A Home Office spokeswoman said: "There is more money and more officers for each Londoner than anywhere else in the country.
"The Government has protected overall police spending in real terms since spending review 2015 and have announced additional funding for counter-terrorism policing.
"In light of the terrorist attacks this year, we are engaging with the police about the demands they are currently facing to ensure they continue to have the resources they need to keep us safe."