Bomb blasts in March 1993 that killed 257 people and injured hundreds in Mumbai also damaged many city streets. (Douglas E. Curran/AFP/Getty Images)

India’s Supreme Court on Tuesday dismissed an appeal by a former accountant convicted of helping plan bombings in 1993 in Mumbai that killed 257 people, clearing the way for his hanging next week.

Yakub Memon was convicted of assisting his brother Tiger Memon and Dawood Ibrahim, the suspected masterminds of the blasts, among the deadliest terrorist attacks in India. Indian investigators believe the two suspects are hiding in neighboring Pakistan.

Yakub Memon, who is in his early 50s, is scheduled to be hanged July 30 in the western state of Maharashtra, whose capital is Mumbai. He has been in prison for two decades.

Twelve bombs — placed at several sites in Mumbai, including the stock exchange, a movie theater, a luxury hotel and busy markets — shook India’s financial capital in March 1993. In addition to those killed, more than 700 were injured.

Indian officials say the bombings were carried out with the help of agents from Pakistan’s intelligence services as reprisal for Hindu-Muslim riots in the city the previous year — triggered by the destruction of a mosque. Those killed in the riots were mostly Muslim. Pakistan denied involvement in the blasts.

Memon has repeatedly said he returned to India and turned himself in to “prove his innocence” and that he had nothing to do with his brother. Indian police say, however, that he was arrested returning from Nepal in 1994.

Memon was convicted in 2007 of plotting to import weapons and explosives by sea from Pakistan. India’s president rejected his mercy petition about a year ago.

Anil Gedam, Memon’s attorney, said he filed another mercy petition to the governor of Maharashtra on Tuesday.

In March 2013, the Supreme Court commuted the death sentences of 10 others convicted in the case to life in prison.

Farhana Shah, a lawyer who had represented the other convicts, said she was “very upset” with the Supreme Court’s decision on Tuesday. “One chance could have been given” to Memon, she said.

Ujjwal Nikam, the public prosecutor in the case, praised the ruling, saying, “The decision today would send out a significant deterrent message.”

Meanwhile, a spokeswoman for the governing Bharatiya Janata Party told reporters in Mumbai, “It is absolutely imperative for people like Yakub Memon to be hanged to death, because the 1993 blast victims know the kind of anxiety they have had to deal with.”

Shaina N.C., the spokeswoman, added, “The law does takes its time, but it’s imperative to send a message that terror has no place in our society.”

Almost 93 percent of those sentenced to death in terrorism cases in India belong to lower-caste groups and religious minorities, according to a study published Tuesday in the Times of India newspaper.

In a statement, Amnesty India said the Supreme Court decision “regrettably puts India in opposition to the global trend towards moving away from the death penalty.” Human Rights Watch urged India to halt the execution.

India has carried out several high-profile hangings in recent years.

In November 2012, India ended an unofficial eight-year-long moratorium on executions when it hanged Ajmal Amir Kasab, the lone surviving Pakistani gunman from the 2008 Mumbai attacks, which killed 166 people. In February 2013, India hanged Afzal Guru, a Kashmiri man convicted of facilitating an attack on the Indian Parliament in 2001.

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