April 22 (Reuters) - UnitedHealth Group said on Monday the February cyberattack at its technology unit Change Healthcare led to breach of protected information, which could cover a 'substantial proportion" of Americans.

The company did not disclose the number of people impacted by the hack.

It said it will take several months before enough information to identify impacted individuals.

(Reporting by Mariam Sunny and Sriparna Roy in Bengaluru; Editing by Krishna Chandra Eluri)