Updated from 4:06 p.m. ET

The

Federal Trade Commission

is leaning toward blocking

America Online's

(AOL)

pending purchase of

Time Warner

(TWX)

unless the companies agree to let competitors use their cable lines, according to

The Washington Post

.

In areas where Time Warner has cable systems, the FTC is worried that the combined company could control high-speed Internet access over cable lines. "As a result, consumers could be forced to accept AOL-Time Warner TV programming and Internet content exclusively," the

Post

said, quoting sources close to the matter. Time Warner is the nation's second biggest cable operator.

The deal faces plenty of hurdles. European authorities also are worried about the power a combined AOL and Time Warner would have. The two are scheduled to present their case for the merger to the European Commission Thursday, according to the

TST Recommends

Associated Press

.

But AOL and Time Warner contend they're already opening Time Warner's cable system. Time Warner recently agreed to give Internet service provider

Juno

(JUNO)

access to its cable lines. And the

Post

quoted an AOL spokeswoman as saying the companies are committed to open access. Neither company returned phone calls seeking comments Monday.

The

Post

reported that the FTC at a minimum wants guarantees that the combined company will continue on the open-access path after the deal closes.

Meanwhile,

The Wall Street Journal

said in its online edition Monday that the combined AOL/Time Warner also may face restrictions on business relationships with

AT&T

(T) - Get Report

, which operates the nation's biggest cable system.