What is the heaviest cricket bat allowed to play international cricket?

As of now, the holder of the heaviest cricket bat is Sachin Tendulkar, which is considered to be the heaviest weighing as high as 1.42 kg. His bats are made in Jalandhar by one fellow Mr Meghna and seasoned in Chandigarh.

http://www.sportskeeda.com/cricket/secret-behind-why-sachin-tendulkar-used-heavy-bat

There is no weight limit for a bat -- In the 18th century bats of over 5lb. were in use and in the 19th.century 4lb. was a common weight.

Law 6: The bat. The bat is no more than 38 inches (96.5cm) in length, and no more than 4.25 inches (10.8 cm) wide. The hand or glove holding the bat is considered part of the bat. Ever since the Heavy Metal incident, a highly publicized marketing attempt by Dennis Lillee, who brought out an aluminium bat during an international game, the laws have provided that the blade of the bat must be made of wood (and in practice, they are made from White Willow wood).

https://en.wikipedia.org/wiki/Laws_of_cricket#Equipment_and_laying_out_the_pitch

The rules of the game limit the allowable size for a bat as not more than 38 in (965 mm) long and the blade may not be more than 4.25 in (108 mm) wide. Bats typically weigh from 2 lb 8 oz to 3 lb (1.1 to 1.4 kg) though there is no standard.

https://en.wikipedia.org/wiki/Cricket_bat