DHAKA, Bangladesh (AP) — The son of a former prime minister of Bangladesh returned home Thursday after more than 17 years in self-imposed exile as a frontrunner to become the nation's next leader in upcoming elections.

Tarique Rahman moved to London in 2008 for medical treatment with permission after he was tortured while in custody during a military-backed government that ruled from 2006 to 2008.

Rahman, 60, is the acting chairman of the Bangladesh Nationalist Party, one of two major political parties in the South Asian nation of more than 170 million people. His return is seen as politically significant ahead of the next election set for Feb. 12 under the current interim government.

A flight carrying Rahman, his wife and daughter arrived at Hazrat Shahjalal International Airport in the capital, Dhaka, late Thursday morning among tight security measures.

Massive crowds of supporters spread across an area about 2 kilometers (1.2 miles) between the airport and a reception venue, where many had stayed overnight. A sea of people also waited at the venue. Rahman’s senior party leaders said earlier they expected “millions.”

After a reception, party officials said Rahman plans to go to a hospital to visit his critically ill mother, former Prime Minister Khaleda Zia, who led a coalition government from 2001 until 2006 when a non-elected government backed by the military came to power during a period of political chaos.

Zia, a former housewife, came to politics after her husband, former military chief and then President Ziaur Rahman, was assassinated in a military coup in 1981. She held power for the first time in 1991 after becoming a key leader in a nine-year movement against a former military dictator who was forced to resign during a mass uprising in 1990.

Zia is considered one of two key figures in Bangladesh politics along with Sheikh Hasina, who was sentenced to death in absentia in November. Hasina was convicted on charges of crimes against humanity involving the crackdown on a mass uprising that ended her 15-year rule in 2024. India has not approved requests to extradite Hasina since she fled there last year.

In recent years, Rahman has been a de facto leader of the Bangladesh Nationalist Party. He regularly joined meetings and rallies online from London, keeping his party united. He was not openly challenged by any party insiders during his absence.

Bangladesh is now at a political crossroads. The interim government headed by Nobel Peace Prize laureate Muhammad Yunus is struggling to maintain law and order and restore confidence while attempting a return to democracy after Hasina's long premiership.

Global human rights groups including Human Rights Watch and the Amnesty International have accused the Yunus government of eroding democratic rights. Liberals in Bangladesh have expressed concerns over press freedom and minority rights and accused Yunus of presiding over a visible rise of Islamists.

Rahman supported Yunus when he took over as the government's chief adviser, but the relationship with his party has been shaky.

Rahman was convicted in several criminal cases during Hasina’s 15-year rule since 2009. Appeals courts under the Yunus government have acquitted him of all criminal charges including involvement of a grenade attacks on a Hasina rally in 2004.