Takata has started enforcing tighter quality controls on a group of parts suppliers as the safety equipment maker boosts production to replace air bags being recalled for a deadly defect.

Takata has come under investigation by U.S. safety regulators and federal prosecutors and intense scrutiny from lawmakers over exploding air bags that have caused five deaths and a recall of 20 million vehicles around the globe.

Since October, the company has launched a number of inspections across its supply network and sent managers to parts makers in Asia and Japan to announce changes, according to Reuters, citing "people involved," who asked not to be identified.

Takata recently confirmed that its representatives would inspect at least 40 suppliers of key parts before the end of 2014 and audit the rest of the firms next year, one of those involved said.

"Takata has become extremely strict when it comes to quality control now," said one of the sources who was present at the meeting.

Inspections that were carried out didn't differ from regular quality checks made by Takata, but they highlighted the sense of urgency and speed with which they have been announced, according to Reuters.

"This time it was different. This inspection had not been planned before and was announced out of the blue during the meeting," said the person involved. "They came to my factory within one, two weeks from setting the date," said the person.

Takata has yet to identify the cause of the defect with its air bags that has left some of them inclined to explode in accidents and shoot shrapnel inside vehicles.

Five deaths have been linked to Takata air bags in Honda Motor Co vehicles, while the recalls around the world affect a range of different automakers.

Takata has 55 factories in 20 countries, eight of which are located in Japan. Takata said that the only facility that makes air bags in Japan is a plant located in Kyushu in southern Japan.

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