Smartphone leader Samsung has reportedly begun rolling out the new Android v4.3 Jelly Bean update to the company's 2013 marquee smartphone Galaxy S4 in India.

The new OS update is believed to be a little over 658MB in size and is available for download via Samsung smartphone PC suite 'Kies', as well as through OTA (Over-The-Air), reported

It is understood that the Android v4.3 Jelly Bean is released in phases; hence it might take a few more days for the update to reach Galaxy S4s across India.

Apart from India, Russia is only other market to receive the update for Exynos based Galaxy S4 (GT-19500) variant. Samsung has also begun releasing the new firmware to LTE variant (GT-19505) in Europe (so far only Germany).

Some of the key improvements to be seen in Galaxy S4 after the OS update include new Knox security app, refreshing user-interface with visual tweaks and improvement in RAM management, leading to increase in performance and efficient usage of battery.

Other major upgrade is that Galaxy S4 will now be compatible with recently released Galaxy Gear smartwatch, which up until now was only compatible with Galaxy Note 3 and Galaxy Note 10.1 (2014 Edition).

According to reports, Samsung's 2012 flagship models - Galaxy S3 and Galaxy Note 2 variants - are also expected to receive the new OS update as early as mid-November or by the end of December this year.