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Former Malaysian Prime Minster Najib Razak (R front) attends a press conference in Kuala Lumpur, Malaysia, May 12, 2018. Najib Razak said Saturday that he is stepping down as head of his United Malays National Organization (UMNO) and the Barisan Nasional (BN) coalition following the defeat in the general elections. The announcement was potentially put forward by the decision of the new government to bar Najib and his wife from leaving the country pending investigation of alleged corruption. (Xinhua)

KUALA LUMPUR, May 12 (Xinhua) -- Former Malaysian Prime Minster Najib Razak said Saturday that he was stepping down as head of his United Malays National Organization (UMNO) and the Barisan Nasional (BN) coalition following the defeat in the general elections.

The announcement was potentially put forward by the decision of the new government to bar Najib and his wife from leaving the country pending investigation of alleged corruption.

"As the president of UMNO and the chairman of Barisan Nasional, I made the decision that I am stepping down as president of UMNO and chairman of Barisan Nasional with immediate effect," Najib told a press conference at the UMNO headquarter in Kuala Lumpur.

The resignation is to take up the responsibility for the defeat in the general elections, he said.

UMNO had led a multi-party coalition to govern Malaysia since the country's independence in 1957 until the election defeat on Wednesday.

Najib said in a statement earlier in the day that he was leaving the country to take a break. He also promised he would announce a decision related to his post as UMNO and BN chief upon returning to the country.

However, it was soon followed by a tweet saying that he had been informed that the immigration department of Malaysia doesn't allow him to leave the country.

"I respect this instruction and will stay in the country with my family," he said.

Mahathir Mohamad, the 92-year-old new prime minister, confirmed later on Saturday that he had instructed the travel ban for Najib and his wife.

"There are a lot of complaints against him, all of which have to be investigated," he told a press conference.

"If we found some of the complaints are valid, we have to act quickly because we don't want to settle with the problem of extradition from other countries."

Mahathir, with 22 years of premiership as UMNO and BN chief, fell over with Najib since 2015 after accusing Najib of corruption related to the state investment company 1MDB. He subsequently joined the opposition and handed his former camp an astonishing election defeat.

Mahathir has vowed to reopen investigation into 1MDB after taking office.