Yemen's ruling General People's Congress (GPC) party on Saturday lambasted as "interference in internal affairs" a US State Department statement urging Sana'a to postpone constitutional amendments, dpa reported.
The Yemeni parliament has begun debating amendments to the country's constitution which would cancel the current two-term limit on the country's presidency, state news agency Saba reported.
The House of Representatives, the lower chamber of parliament, had agreed in principle to debate the constitutional amendments but referred it to a sub-committee for further study.
Also among the proposed changes is one to reduce the president's term of office from seven to five years, parliamentary sources told the German Press Agency dpa.
On Saturday, around 2,000 opposition activists protested outside the parliament's compound in Sana'a against the amendments.
They carried placards reading: "The constitutional amendments are a retreat from the republican regime and democracy" and "No to re- election, no to inheritance of power."
President Ali Abdullah Saleh, 68, has been at the helm of Yemen since 1978. He was elected for the first time through direct universal suffrage in 1999, and re-elected for a second seven-year term in 2006. His current tenure ends in 2013.
In a statement on Friday, the US State Department spokesman Mark C Toner urged the Yemeni government and the opposition to resume dialogue on electoral reforms.
"We urgently call on all parties to delay parliamentary action and to return to the negotiating table to reach an agreement that will be welcomed by the Yemeni people as well as Yemen's friends," Toner said.
The debate on the constitutional changes began a few days after President Saleh said his government would forge ahead with preparations for parliamentary elections next year amid speculation of a boycott by opposition parties.
Yemen's main opposition parties, grouped under the umbrella of the Joint Meeting Parties (JMP), had warned that the ongoing election preparations would only produce a rigged vote and threatened to boycott the poll.
The legislative elections were originally scheduled for April 2009, but the JMP and GPC agreed in February 2009 to postpone the vote for two years in order to provide time for a national dialogue on electoral reforms.
Both sides have since been trading accusations of obstructing the dialogue.
"We continue to believe that the interests of the Yemeni people will be best served through that process of negotiations," the US official said.
The ruling GPC party then denounced the state department's call for postponing the debate on constitutional amendments as an "interference in the internal affairs of peoples and an infringe on national sovereignty as the parliament in any country represents the will of the people and their choices."
It said the US call "lacks discretion and is not up to the level of responsibility and diplomatic norms."
The planned constitutional changes were "legal and constitutional procedures that stem from the will of the people and its higher interests and not according to the wishes or whims of foreign parties," the GPC said in its statement.
JMP parties have frequently called for reforming the electoral system before any poll can be held.
The JMP includes the main opposition party Islah and the Yemeni Socialist Party, as well as four other smaller opposition parties.