Police seized 42 pounds of suspected heroin worth an estimated $5 million when they arrested two men in East Boston Wednesday afternoon, authorities said.

The seizure of the drug, one of the largest in recent years, led to the arrest of 35-year-old Miguel Antonio Rivera of Chelsea and 49-year-old Santa Cruz of Norwalk, Conn., on heroin trafficking charges. They are to be arraigned today in East Boston Municipal Court.

Federal immigration officials have filed a detainer against Rivera, meaning that if he is able to post bail on the drug charges he will be taken into custody by the US Immigration and Customs Enforcement agency for allegedly being in the country illegally.

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The suspected heroin is now in the control of the US Drug Enforcement Administration, prosecutors noted. The two men were arrested by State and Boston police, officials said.

No further details were immediately available of the investigation that led to the arrest.