Mexican President Enrique Pena Nieto is pledging an investigation into purchases of luxury homes by himself, his wife and his finance secretary from government contractors.

Pena Nieto said Tuesday he has asked the Public Administration Department to investigate the purchases, which have cast suspicion over his administration.

The department functions as an anti-corruption watchdog agency. The president said the results of the probe would be reviewed by a panel of experts.

When he was governor of the State of Mexico in 2005, Pena Nieto bought a house from a company that got government contracts.

Finance Secretary Luis Videgaray and First Lady Angelica Rivera later both bought houses from another government contractor, which also financed the purchases.

All three have denied they did anything improper.