Mukesh Ambani-run Reliance Industries Ltd. (RIL) has raised its offer for LyondellBasell Industries to $13.5 billion, but may have to sweeten it further as the board of the bankrupt Netherlands-based chemicals maker appeared unlikely to accept the improved offer.

RIL wrote to Lyondell raising its valuation of the world’s third-largest chemicals maker to about $13.5 billion from the $12 billion initially put forward in November, sources familiar with the transaction said.

The revised offer has not found much support from the board of Lyondell and RIL may sweeten the offer further, the sources said, adding that the company had time till February to make another offer.

RIL spokesperson declined to comment.

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