Protesters in Sanaa and other Yemeni cities have been demanding Saleh's overthrow for months now [Reuters]
Shelling attacks on the southwest Yemeni town of Taiz, a site of frequent anti-government protests, have left seven civilians dead and 22 others injured.
Local residents were targeted in four parts of the town on Tuesday by the government's Republican Guard and special police units.
Locals launched appeals for help, but were unable to get the victims to safety, a medical source told the AFP news agency.
"Government forces, from the hills and from security barricades, and from al-Thawra hospital and Freedom Square, they are shelling," Abdulkader al-Guneid, a resident in the town, told the Reuters news agency.
The shelling continued into the night, he said, without giving any information on what sparked the bombardment.
Sources told Al Jazeera that six people wounded in the shelling had reached hospital and more were expected but added that it was not immediately possible to determine the number of casualties.
Taiz, 270km southwest of the capital Sanaa, is one of the main focuses of the protest movement against the government of Ali Abdullah Saleh.
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State television blamed opposition fighters for starting the fighting and said four government troops had been wounded.
Taiz, and other opposition hubs, have been paralysed by nearly nine months of protests to demand an end to Saleh's 33-year rule.
In Sanaa, mortar fire killed two civilians and wounded six in fighting between forces loyal to the president and troops siding with anti-government protesters.
A doctor said a mortar round hit a market in a district contested by government troops and those of dissident general Ali Mohsen, a former Saleh ally. One of the dead was 14 years old.
The doctor said he had received death threats for helping the wounded and a bag of bullets was thrown into his yard as a warning.
"We are treating these protesters and civilians but the government wants to threaten us to stop us doing our job. Now they are threatening my family," he said.
Last month in Sanaa, political deadlock gave way to a military showdown between Saleh loyalists and Mohsen's forces. More than 100 people were killed in the fighting, most of them protesters caught in the middle.
Tens of thousands of protesters took to the streets again on Tuesday afternoon to draw attention to their demands before an expected briefing by Jamal Benomar, the UN envoy to Yemen, before the world body's Security Council.
The opposition cast doubt on any future dialogue with the government, which it blamed for the apparent failure of mediation attempts by Benomar, who left Yemen empty-handed on Monday.
"The dialogue with the regime has stopped and there is no form of dialogue after Saleh wasted all opportunities for dialogue, which led to the departure of the UN envoy," Mohammed al-Sabri, an opposition spokesman, said.
Benomar spent two weeks in Yemen trying to negotiate a deal but left without announcing a breakthrough after days of mediating between the government and the opposition.
Source: Al Jazeera and agencies