CBS says it will become the first network to simulcast its evening news broadcast online, starting the night of Katie Couric's debut as anchor Sept. 5.

ABC streams a "World News" unique to the Internet audience and NBC's Brian Williams contributes to both a video and written blog.

However, NBC's replay of "Nightly News" isn't available until after it has aired on TV. Network affiliates have been concerned they would lose parts of their TV audiences.

But CBS News President Sean McManus said the network reached a deal with its affiliates by arguing the program will reach a different audience online. People will have to specifically register online to see the webcast to prevent people from watching the news before it is broadcast in their areas, CBS said.