The personal animosity between Bangladesh's rival political leaders and the seemingly endless bickering it feeds on, has found a new focus in a row over opposition chief Khaleda Zia's date of birth. Prime Minister Sheikh Hasina's ruling Awami League party has accused the premier's arch rival of changing her birthday -- not out of vanity but out of spite. Former premier Zia celebrated her 65th birthday on Saturday. The date, August 15, is also the anniversary of the 1975 assassination of Hasina's father, Sheikh Mujibur Rahman, who led the country to independence from Pakistan in 1971. 'Khaleda Zia's educational certificate shows her birth date is September 5. Her marriage certificate shows she was born in late August. She changed the birthday to August 15 in the 1990s,' health minister A.F.M Ruhul Haque said. 'She did it deliberately to celebrate the killings of August 15,' Haque said. Sheikh Mujib was assassinated along with 14 family members by a group of army officers. Hasina was abroad at the time. Altering one's date of birth is not unusual in Bangladesh. It is often done to circumvent age-related restrictions on university applications and official retirement. Registration at the time of birth only became mandatory in Bangladesh in 2006. Zia's Bangladesh Nationalist Party (BNP) dismissed the suggestion that any dates had been changed and accused Hasina's party of playing politics. 'We condemned the brutal killings of Sheikh Mujib, but what can we do if someone is born on that day?' said BNP spokesman Nazrul Islam Khan. 'Khaleda Zia has been observing her birthday on August 15 for decades and the Awami League is trying to make it a political issue,' he told selfnews. Zia and Hasina, who have dominated Bangladesh's political scene for almost two decades, are known as the 'battling begums' for a mutual dislike that is as intense as it is personal. During her first stint as premier, from 1996 to 2001, Hasina declared August 15 a public holiday and National Mourning Day, but Zia cancelled it in 2002 when she was in power. A caretaker, army-backed government reinstated it last year. 