Pakistan suspended mobile phone services nationwide on Thursday for election day, the interior ministry citing the need to “maintain law and order”.

“It has been decided to temporarily suspend the mobile service across the country,” a ministry spokesman said in a statement.

The spokesman said “precious lives have been lost” in recent militant attacks in Pakistan and “security measures are essential to maintain law and order situation and to deal with potential threats”.

AFP journalists in the capital Islamabad could not access mobile internet services as polls opened at 8am local time (3am GMT), while there were also reports of poor access in the southern city of Karachi.

Two blasts near election offices on Wednesday killed at least 30 people in the southwestern province of Balochistan.

Islamic State claimed responsibility for the blasts in a message on its Telegram channel. Several other groups, including the Islamist Pakistani Taliban (TTP) and separatist Baloch militants oppose the Pakistani state and have also carried out attacks in recent months.

The country is on high alert with tens of thousands of troops and paramilitary soldiers on duty, including at polling stations. Pakistan also said it was closing its borders with Iran and Afghanistan for the day for security purposes.

Unofficial first results in the election are expected a few hours after voting closes at 5pm local time (12pm GMT) and a clear picture is likely to emerge early on Friday.

The main contests are expected to be between candidates backed by Imran Khan, whose Pakistan Tehreek-e-Insaf (PTI) party won the last national election, and the Pakistan Muslim League (PML-N) of three-time premier Nawaz Sharif, who is considered the front-runner.

Bilawal Bhutto Zardari, the 35-year-old son of former premier Benazir Bhutto, has also run an aggressive campaign in an outside bid for the top office.

Despite the cold, long queues began forming at polling stations hours before voting was due to start. “The country is at stake, why should I come late?” said 86-year-old Mumtaz, as she queued up in Islamabad.

Businessman Imran Sheikh, 52, said he was voting for an independent candidate backed by Imran Khan to “make it right”.

“They are trying everything in their power to make sure people don’t vote,” he said, referring to the military that has long held sway over Pakistani politics.

“But many people like me and others I know will make sure we get out and vote,” he added.

Analysts say there may be no clear winner but the powerful generals could play a role. The military has dominated the nuclear-armed country either directly or indirectly in its 76 years of independence, but for several years it has maintained it does not interfere in politics.

“The deciding factor is which side the powerful military and its security agencies are on,” said Abbas Nasir, a columnist.

“Only a huge turnout in favour of PTI can change its fortunes.”