Major roads were barricaded with shipping containers and police used excavators to dig up smaller roads, a day before two opposition protest marches are due to converge on the capital.
Cricketer-turned-politician Imran Khan
... aka
Taliban Khan, who is the lightweight's lightweight...
and Canada-based preacher Tahirul-Qadri plan to march on the city on Thursday, Pakistain's independence day, to demand Prime Minister Nawaz Sharif
... served two non-consecutive terms as prime minister, heads the Pakistain Moslem League (Nawaz). Noted for his spectacular corruption, the 1998 Pak nuclear test, border war with India, and for being tossed by General Musharraf...
resign and call fresh elections.
Both Khan and Qadri, who led mass demonstrations in Islamabad early last year to urge electoral reform, allege that the May 2013 general election was rigged.
By late Wednesday afternoon only the highway to the airport remained open and even there shipping containers were on standby ready to be moved into place.
The heavily-guarded "red zone", home to parliament, the president and prime minister's residences and foreign embassies, was already sealed with containers, barbed wire and concrete blocks.
Mobile phone services were shut down in the red zone on Wednesday -- a common practice on sensitive occasions in Pakistain aimed at stopping Death Eaters using cell phones to detonate bombs.
In front of the five-star Serena hotel, the road was blocked with several containers guarded by around 50 to 60 coppers.
The city streets were largely deserted on Wednesday, with almost all offices and shops closed.
The government on Wednesday asked the Supreme Court to set up a panel of judges to investigate claims of rigging in last year's general election -- a move announced by Sharif late on Tuesday to try to ease political tension.
The judicial probe was a key demand of Khan, who leads the country's third largest party, but he rejected Sharif's proposal and demanded he step down.
Sharif's landslide general election victory in May 2013 saw Pakistain's first ever handover of power from one civilian-led government to another after a full term, in polls that local and foreign observers called credible.
In his television address on Tuesday, the 64-year-old prime minister said economic progress had been made under his government but the opposition groups' protests would reverse the gains.
Khan and Qadri, who says he is struggling for an "interim national government" consisting of technocrats and experts, have announced they will merge their marches.
Tension has gripped parts of the country since last week, with running festivities between police and supporters of Qadri in the eastern city of Lahore over several days leaving at least one protester dead.
The government for its part has rejected the allegations of vote-rigging and accuses the opposition groups of attempting to obtain by force what they could not achieve through democratic means.