India's government ordered its Serious Fraud Office to investigate two companies that may be linked to the fraud at Satyam Computer Services Ltd. regarded as the largest in India's corporate history.

The probe will be extended to include Maytas Properties Ltd and Maytas Infra Ltd, two companies that were attempted to be purchased by Satyam in mid-December, before the software maker's CEO Ramalinga Raju confessed of falsifying the company's profits for about $1 billion.

Maytas Infra Ltd is a construction company in which Raju and his family had a stake of 36 percent. Maytas' CEO resigned on January 14, the company said on Monday, Reuters reports.

Maytas and Satyam spell the same backwards.