Tomar, who is also the Registrar of Firms and Societies in the Government of National Capital Territory of Delhi (GNCTD), had allegedly demanded the bribe from the president of the society, which has a huge land bank and substantial deposits in the bank, the CBI claimed.
The society, which was registered in 1978, had approached his office for certification of its newly-elected executive members as well as the president.
The complainant, however, informed CBI's anti-corruption branch, which laid a trap and arrested Tomar while he was allegedly accepting Rs 10 lakh as the first instalment of the bribe.
Sources said that, before the arrest, CBI had registered a case under the Prevention of Corruption Act and monitored his telephone calls.
The executive committee was required to be certified by the Registrar, Firms and Societies, including the names of the office bearers.
Searches were carried out at Tomar's office and residence, the sources said. They claimed that sleuths had recovered nearly Rs 5 lakh in cash from his home.