General Motors has now agreed a compensation payout to families of 21 people killed in its cars in crashes related to faulty ignition switches.

The automaker has so far received 143 claims of fatalities in applications to the victims’ compensation fund administered by top US lawyer Kenneth Feinberg.

The tallies are up from 19 and 125, respectively, a week ago.

In a document published on the internet (www.GMIgnitionCompensation.com), the GM Ignition Compensation Claims Resolution Facility said claims determined eligible to date totalled 37 including four 'Category One' injury claims and 12 in 'Category Two'.

Of the total of 675 claims made so far, 65 are Category One and 467 Category Two.

Feinberg's team has defined Category One claims as "Physical Injuries resulting in Quadriplegia, Paraplegia, Double Amputation, Permanent Brain Damage or Pervasive Burns" and Category Two as "Physical Injuries requiring hospitalisation (or outpatient medical treatment) within 48 hours of the accident".

GM has maintained only 13 fatalities were connected to the defective switches. The switches can be accidentally knocked, shutting off engine, power steering, power brakes and airbags.

"GM was asking its engineers can you definitively say ignition switch defects caused the accident," Feinberg earlier told Bloomberg Television.

"Our standard, as you know, is much more liberal. It’s easier to apply. It’s a legal standard, was the ignition switch the proximate cause, a substantial likelihood as the cause of the accident?"

Feinberg reportedly said then he expected the number of fatalities to increase as more claims came in, though he wouldn’t give an estimate as to how high. He also declined to speculate how much GM could pay out. The automaker in July had said it was setting aside $400m to $600m to pay victims.

GM has also said it would will abide by whatever determinations Feinberg makes.

Feinberg said last week GM’s official tally only included the drivers but the compensation fund uses a broader legal definition that makes more people eligible for payment, including the occupants of other vehicles and pedestrians if they were struck by a car with a faulty ignition switch.