(Adds BT comment, share price reaction)
LONDON, March 22 (Reuters) - BT, the owner ofBritain's biggest fixed-line network, must install businesslines more quickly and significantly cut the prices it chargesrivals to use them, the country's telecoms regulator said
Ofcom's demands on Tuesday come less than a month after itsaid it would impose higher service standards on BT's networksunit Openreach in its review of the communications market.
BT will have to install dedicated high-speed lines forbusinesses in 46 working days by the end of March 2017, and 40working days the following year, down from a current 48 days.
It would also have to reduce prices for the leased lines,which are often used by companies such as Vodafone andTalkTalk, and propose prices and terms for rivals toinstall their own equipment to use its fibre connections, aconcept know as "dark fibre" by Sept 1.
Shares in BT fell to a five-month low of 440 pence onTuesday morning, before recovering most of the loss to tradedown 0.8 percent at 446 pence at 1137 GMT.
BT said it was committed to doing a better job for businesscustomers, but noted that the installation of high-speedethernet connections could be complex.
"The required ethernet price cuts and the introduction ofdark fibre will not help to underpin service improvement," BTsaid in a statement.
Allowing rivals to use its fibre connections would introducean unnecessary layer of complexity and would deter others frombuilding their own fibre networks, it added. (Reporting by Paul Sandle; Editing by Sarah Young and AlexanderSmith)