UPDATE 1-Two small US banks fail; brings 2008 tally to 15

(Adds acquirers, cost to insurance fund, details on closures, background)

WASHINGTON, Oct 10 (Reuters) - U.S. regulators took over two small banks on Friday, in Michigan and Illinois, bringing the tally of bank failures to 15 so far this year.

The Federal Deposit Insurance Corp. said it had seized Main Street Bank of Northville, Michigan, and Meridian Bank of Eldred, Illinois.

Main Street Bank had total assets of $98 million and total deposits of $86 million as of Oct. 7, the FDIC said, while Meridian Bank had $39.2 million in total assets and $36.9 million in total deposits as of Sept. 25.

The two failures are expected to cost the U.S. bank deposit insurance fund, that stood at around $45 billion at the end of June, between $46 million and $53.5 million, the FDIC said.

The financial rescue plan passed by Congress last week temporarily raised the limits on deposit insurance to $250,000 per account from $100,000.

Monroe Bank & Trust of Monroe, Michigan, agreed to acquire all the deposits of Main Street Bank. National Bank of Hillsboro, Illinois, agreed to acquire all the deposits of Meridian Bank.

Customers can access their money over the weekend by check, teller machine or debit card, the FDIC said.

The U.S. banking industry has been under pressure from a housing slump and sluggish economy that has caused financial institutions to post stunning write-downs and losses.

Congress last week authorized the U.S. Treasury to spend up to $700 billion to unfreeze credit markets and shore up public confidence.

Treasury Secretary Henry Paulson announced Friday evening that the United States was developing plans to directly inject capital into financial institutions by purchasing equity.

The FDIC said depositors at the two banks that failed on Friday will have uninterrupted access to their money, and will still be insured with the new institutions.

Main Street Bank's two offices will reopen on Saturday as branches of Monroe Bank & Trust. Meridian Bank's four offices in Altamont, Carlyle, and Eldred will reopen for normal hours on Saturday, and the Alton office will reopen Tuesday as branches of National Bank.

The FDIC said the deposit assumptions were the least costly alternatives for its insurance fund, dented by increased bank failures this year, including Washington Mutual, the largest bank failure in U.S. history.

Just three banks failed in 2007.

The FDIC on Tuesday proposed more than doubling the average fee that U.S. banks pay into the insurance fund, in an effort to replenish it.

The agency expects bank failures will cost the fund about $40 billion from 2008 to 2013, with almost $13 billion of that amount used this year. (Reporting by Karey Wutkowski; Editing by Tim Dobbyn)