A one-year-old baby is among the family group that is thought to have fled to Syria after a holiday in Bangladesh.
Muhammed Abdul Mannan, 75, his wife Minera Khatun, 53, of Spencer Road, Luton, their daughter Rajia Khanom, 21, and sons Mohammed Zayd Hussain, 25, Mohammed Toufique Hussain, 19, Mohammed Abil Kashem Saker, 31, his wife Sheida Khanam, 27, Mohammed Saleh Hussain, 26, and his wife Roshanara Begum, 24, along with three children, aged between one and 11, were reported missing after failing to return home from viditing their home country in May.
Police are working with relatives who are still in the UK to trace them and asked anyone with any information about the 12 to call police on 101.
People can also visit www.preventtragedies.co.uk for information and advice for people who may be worried about a friend or loved one.
More top news
The young backpacker from Essex was allegedly strangled following a date.
Voight is one of the few Hollywood actors who is an outspoken backer of Donald Trump.
The renewable power system is helping to heat a farmhouse in Snowdonia, where the first bible translated into Welsh is on display.