Twenty-six men believed to belong to the pro-government "Shabiha" armed group have been killed in Syria's northern Aleppo province, an activist monitoring group has said.

A video link sent by the UK-based Syrian Observatory for Human Rights (SOHR) on Friday appeared to show several men covered in blood and piled on top of each other on the side of a road.

Some of the men wore army fatigues but some were just wearing t-shirts.

The circumstances of the killings were not immediately clear, but in the video, which could not independently be verified, the narrator said the dead were members of the "shabiha".

Earlier, Syrian state television reported that armed fighters had kidnapped and killed 25 people in Darat Azzah village in Aleppo province.

"Armed terrorist groups committed a brutal massacre against 25 citizens in Darat Azzah," the station reported.

The observatory appeared to be refering to the same incident as Syrian state television, Reuters news agency reported.

Also on Friday, the SOHR said four senior army officers had defected from the Syrian government.

The group provided a video purporting to show two brigadier generals and two colonels who declared they were joining the opposition.

The group said the defections came on Thursday, the same day a Syria fighter pilot flew his MiG-21 warplane to neighbouring Jordan, where he was given asylum.

Thousands of soldiers have abandoned the regime, but most are low-level conscripts.

The Free Syria Army, the loosely linked group of opposition fighters, is made up largely of defectors.

Humanitarian need escalates 

Also on Friday, the UN reported that the number of people needing humanitarian assistance in Syria had risen to 1.5 million from the previous estimate of one million.

They reported that the escalating violence continued to drive people from their homes.

Aid agencies face "significant" constraints in reaching growing numbers of civilians who need basic goods and protection, the UN Office for the Co-ordination of Humanitarian Affairs (OCHA) said.

"Up to 1.5 million people now need humanitarian assistance in Syria," Jens Laerke, spokesman for the organisation told a news briefing in Geneva.

They include 350,000 in northern Idlib province and about 250,000 in the flashpoint city of Homs, where more than 100 public buildings have been turned into temporary shelters for people who have fled their homes, an OCHA statement said.

The UN's World Food Programme (WFP) had distributed food to 461,000 Syrians by mid-June and aims to increase that number to 850,000 in July, the statement said.

The WFP, which announced on June 5 that it had reached an agreement with Syrian authorities to implement a major assistance programme, has been stymied by the deteriorating security situation, said Laerke.

Reconnaissance missions have been conducted and humanitarian hubs will be established initially in Homs and Deir al-Zor in the east.

"However, given the deteriorating security situation, the deployment of staff to field locations is on hold", the OCHA said.

More than 96,000 Syrian refugees have now been registered in Iraq, Jordan, Lebanon and Turkey - a rise of nearly 20,000 since May 31, it said, quoting the UN refugee agency, the UNHCR.

Source: Agencies