DETROIT – A government safety agency is fining General Motors $7,000 a day, saying the company failed to fully respond to its requests for information about a faulty ignition switch by an April 3 deadline.

The National Highway Traffic Safety Administration said in a letter to GM on Tuesday that the company already owes $28,000 in fines, and they will accrue at $7,000 per day until all the information is provided.

In February, the agency began investigating whether GM was slow to provide information and respond to problems with the switch that has been linked to at least 13 deaths. GM has admitted knowing that the switch was defective at least a decade ago but failed to start recalling 2.6 million compact cars worldwide until this year.

In a letter to Lucy Clark Dougherty, GM North America vice president and legal counsel, NHTSA's chief counsel, O. Kevin Vincent, said the company stated it did not respond to all the agency's requests because of an investigation for GM by former U.S. Attorney Anton Valukas.

But Vincent wrote that GM's reasoning wasn't valid. "Mr. Valukas' investigation is irrelevant to GM's legal obligation to timely respond … and fully cooperate with NHTSA."

The deepening rift between GM and the safety agency was apparent in congressional hearings last week. NHTSA Acting Administrator David Friedman blamed GM for not acting sooner to warn consumers. Friedman testified GM had information connecting defective switches to the nondeployment of air bags but didn't share it with the agency until last month.

GM said in a statement that it has fully cooperated and will keep providing responses as soon as they are available. "We will do so with a goal of being accurate as well as timely," it said, giving no indication of when GM would fully comply.

Associated Press