LG Electronics Inc reported on Thursday its strongest quarterly profit in more than three years, beating analyst estimates thanks to a pickup in television sales and a turnaround in its mobile phone business. The worlds second-largest TV maker after local rival Samsung Electronics Co Ltd said profit at its TV arm improved in April-June from a year earlier, while its smartphone shipments rose 20 percent to a record 14.5 million handsets. A key factor to watch is how well the G3 smartphone fares in the United States, but the outlook appears to be bright given the second-quarter numbers. For the April-June period, LG Electronics reported an operating profit of 606 billion won ($589.04 million), compared with a 524 billion won mean estimate of 39 analysts polled by Thomson Reuters I/B/E/S. That was LGs best operating profit since at least 2011. Shares of LG Electronics were trading up 4.6 percent as the wider market traded flat, extending gains following the companys earnings disclosure.