MUMBAI, September 27 (Reuters) - Reliance Communications, the most leveraged among the nation's listed phone carriers, aims to cut its debt by more than three-quarters within a year, Chairman Anil Ambani said on Tuesday. Speaking at the company's annual shareholders' meeting in Mumbai, Ambani also said its deal with Reliance Jio Infocomm, a new telecoms venture of his brother, to jointly offer 4G services was like a "virtual merger" between the two companies and would help Reliance Communications cut costs. Reliance Communications, India's fourth-biggest mobile phone carrier by subscribers, has a net debt of 420 billion rupees ($6.3 billion), or more than five times its annual earnings before interest, tax, depreciation and amortisation (EBITDA). The heavy debt load has weighed on its stock, which has lost nearly 95 percent of its value since hitting a high in 2008. "My target is we will see a debt reduction by more than 75 percent of existing debt in a year's time," billionaire Ambani told shareholders. Reliance Communications is merging its wireless business with smaller rival Aircel and has said the deal will cut its debt by 200 billion rupees as it transfers part of the debt to the new venture. The company, which is also looking to sell its mobile towers business to cut debt, has said it expected a deal for that by October. Ambani on Tuesday said the company would "shortly" announce a deal, without giving details. But Moody's Investors Service this month placed Reliance's "Ba3" rating under review for a downgrade, saying debt levels would remain above its comfort even after the Aircel merger while citing uncertainty behind the closure of the tower sale. JIO BOOST Reliance Jio, backed by Anil's elder brother and India's richest man Mukesh Ambani, started commercial services this month and is giving away free calls and data services until the end of December. That has triggered a price war in India's highly-competitive wireless sector, forcing market leaders Bharti Airtel and Vodafone India to cut rates. Jio and Reliance Communications have agreed to share their mobile spectrum. Jio also has an agreement to use Reliance Communications' mobile towers. "For all practical purposes, we have accomplished a virtual merger between Jio and RCom (Reliance Communications)," Anil Ambani said, adding his company had crossed 1 million 4G subscribers within 90 days of starting the services. The two companies do not have ownership stakes in each other after a split in 2005 carved up the Reliance business empire among the two brothers.