UPDATE 1-Mitsubishi UFJ unit to buy PNC's Smartstreet

May 9 (Reuters) - Mitsubishi UFJ's US unit Union Bank said it would buy PNC Financial's Smartstreet homeowners associations business, as the largest Japanese lender by assets looks to expand internationally.

Smartstreet provides banking services like payment processing, lockbox services and remote deposit capture to community associations and management companies. PNC Financial acquired the business through its acquisition of Royal Bank of Canada's US unit.

Union Bank will buy the unit for about 10 billion yen ($125.71 million), Japanese business daily the Nikkei said.

The acquisition would boost Union Bank's deposits from homeowners association-related services to about $1.7 billion dollars, making it No. 2 in the US market, the daily said.

The deal is expected to be completed in the fall.

Earlier this year, Union Bank said it would buy California lender Pacific Capital Bancorp for about $1.5 billion.

Mitsubishi UFJ Financial Group's banking unit may spend over $12.3 billion in the next three years on overseas acquisitions to diversify from a slowing domestic market, a senior executive told Reuters in April.