Pakistani authorities have stepped up security to quell the prospect of protest marches against Prime Minister Nawaz Sharif's government.

Security forces on Wednesday placed shipping containers across roads to try and halt protesters and suspended mobile phone services in some areas.

The move comes as opposition leader Imran Khan and religious scholar Dr Tahir ul Qadri both planned to go ahead with protest marches in Islamabad on Pakistan's Independence Day on Thursday.

Khan said last year's elections were rigged and that Sharif has been elected on a "fake mandate".

Qadri, a Pakistani Muslim leader who's also a Canadian national, has previously asserted that he wanted to bring about a revolution, as the present system has "failed to deliver justice".

The mass demonstration is scheduled from the eastern city of Lahore to the capital Islamabad.

Al Jazeera's Asad Hashim in Islamabad said there was an apparent attempt by Lahore High Court to block the planned protests.

As of Tuesday, Pakistani authorities summoned 6,000 police to Islamabad from outside the capital as well as 3,000 border guards and had blocked some roads leading into the city.

Sharif said in a televised address on Tuesday that he would commission a Supreme Court committee to look into allegations of vote-rigging in the 2013 general election.

In his address Sharif warned that "no-one will be allowed to create anarchy and play with the constitution".

"I respect the right to protest within the limits of the law, but no one will be allowed to destabilise the country," Sharif said.

His proposal was seen as an olive branch for the opposition, but Khan dismissed the offer, saying he could not trust any commission as long as Sharif remained in power.

"Whatever happens, we will march on August 14. If you stop us, you will be digging your own grave," he said, referring to Sharif.

Source: Agencies