Myanmar has sealed its border with Bangladesh, suspending authorised movement of people and cargo between the two countries, officials said on Saturday.
They said the 320-km (200-mile) border had been closed since August 23, two days after a grenade attack at an opposition rally in Dhaka killed 19 people and wounded 150.
"Apparently it (Myanmar) is trying to stop criminals from moving into its territory from Bangladesh," said an officer of the Bangladesh Rifles (BDR) border guard.
He said Yangon had given no notice of the closure but the Myanmar border force had confirmed after a BDR query that they were acting on directives from higher authorities.
"They did it unilaterally, halting operations at the Teknaf transit point," said the BDR officer at Teknaf, 500 km (300 miles) south-east of Dhaka and the sole crossing on the Bangladesh-Myanmar border.
"Lawful movement of people and cargo has remained stopped since August 23," he added.
The grenades exploded in Dhaka at a rally of the opposition Awami League just after party chief Sheikh Hasina, a former prime minister, ended a speech to thousands of followers.
It was the bloodiest in a series of unexplained blasts across the country since 2000 - at opposition rallies, concerts, mosques and cinema halls - in which at least 150 people have been killed and hundreds wounded. No one has been charged with any of the attacks.
Hasina said the grenade incident had been intended to kill her and blamed militants close to Islamic partners in Prime Minister Begum Khaleda Zia's coalition.
Khaleda and her Bangladesh Nationalist Party (BNP) rejected the allegation but, analysts said, the government finally appeared to be taking the violence seriously.