UPDATE 2-Brazil's Braskem says gas supply in Mexico restarted, share rise

(Updates with share reaction)

RIO DE JANEIRO, March 1 (Reuters) - Braskem Idesa (BI), a Mexican unit of Brazilian petrochemical producer Braskem SA , has begun to receive natural gas from Mexican agency Cenagas, after supply of the fuel was cut off in December, it said in a Monday securities filing.

In the filing, Braskem said it had signed a new service contract with Cenagas, along with a memorandum of understanding with Mexico's state-run oil firm Pemex regarding potential amendments to an ethane supply contract.

The news sent Brazil-listed Braskem shares up 6.3% in early trading on Monday, significantly outpacing Brazil's benchmark Bovespa equities index, which had climbed 1.5%.

"With the signature of these documents by BI, BI has started to receive, starting now, natural gas delivery, which had been unilaterally cut off," Braskem said.

In December, Mexican President Andres Manuel Lopez-Obrador announced that Cenagas would cease to supply natural gas to the Braskem Idesa Etileno XXI plant by the Gulf Coast.

The populist leader had previously complained of the terms of a contract between state-run oil firm Pemex and the plant for the supply of ethane, another type of gas. The plant produces polyethylene, a plastic commonly used in packaging.

Braskem said the ethane supply contract remains in place for now, but it could not predict the outcome of any negotiations regarding supply of the gas. (Reporting by Gram Slattery in Rio de Janeiro and Paula Laier in Sao Paulo Dditing by Louise Heavens)