A fault in an undersea cable has crippled many of Pakistan's internet and mobile phone links overseas.
Pakistan has more than 10 million internet users
The fault occurred late on Monday and systems are still down. One internet official said it could take two weeks to repair.
The fault has been traced to a point in the Arabian Sea 35km (21 miles) south of Karachi and technicians from Dubai are travelling to make repairs.
Pakistan has more than 10 million internet users.
Disruption could also occur in India, the United Arab Emirates, Djibouti and Oman, which are also linked by the cable, Pakistani telecommunications officials said.
Ground to halt
Shahid Ahmed, chief engineer of Pakistan Telecommunication (PTCL), which operates the link, said of the repair work: "This is a highly sophisticated operation and only specialised companies can undertake such a delicate task under the sea.
"Pakistan has no such ability."
Mr Ahmed said the consortium of 92 countries that owns the cable had asked operating agent Singtel of Singapore to fix the fault.
He said Singtel had called in Dubai-based E-Marine but its ship could take a day just to reach the site.
Internet Service Providers Association general secretary, VA Abdi, said: "I fear it could take two weeks to repair because it will require the removal of the faulty portion of the cable.
"The cable provides Pakistan's major outer communication means and its fault has disrupted almost all communications with the rest of the world."
In Pakistan, much internet-based work ground to a halt.
Rahim Kothari, a foreign exchange dealer in Karachi, told the Reuters agency: "We're sitting here idle doing nothing. Trading volume has fallen by almost 80%."