"Twenty tunnels are partially back to work since Sunday out of the 250 tunnels still closed because of Egyptian security measures on borders," a source in the Hamas borders and tunnels authority told Anadolu Agency.
The operational tunnels are being used to smuggle food, fuel and construction materials into Gaza.
About 40 to 50 trucks of cement are smuggled through the tunnels per day, down from 300 to 400 trucks daily.
The source said about 3 million litres of fuel were smuggled through the tunnels in the past five days.
Egypt has launched a security crackdown in Sinai in the run up to mass protests that led to the army's removal of elected president Mohammad Morsi.
The security crackdown has caused a fuel shortage in Gaza and doubled the prices of building materials.
An owner of a fuel-smuggling tunnel says the army reinforcements are disrupting the smuggling operations through tunnels.
"The smuggling operations are going slowly and at high risks because of the big security reinforcements at Gaza borders," he told AA.
He said army troops destroyed four fuel pumps and a tanker inside a smuggling tunnel on Friday.
But he said eight tunnels now operate to smuggle construction materials into Gaza, out of 50 tunnels.
"We are now able to smuggle 400 tons and cement and 400 tons of gravel, from more than 2,000 tons in the past," he said.
Another tunnel owner agrees: "Smuggling is being done with great difficulty and at high risks to the life of workers because of army attacks on the tunnels".
Underground tunnels are a lifeline for the Palestinians living in Gaza, which has been under an Israeli blockade since 2006.
Judges at the International Criminal Court have ruled that former Ivory Coast president Laurent Gbagbo is fit to stand trial for his alleged involvement in deadly post-election violence in his country.
Authorities in France have used state of emergency powers to place 24 activists under house arrest as France continues its ban on public demonstrations ahead of the scheduled climate talks.
A 24-year-old arms dealer is suspected of delivering weapons used in terrorist attacks in Paris
Suicide bomber attacks procession of Shia Muslims in northwestern part of Nigeria
Ambassadors of numerous countries, UN and African Union officials as well as Ethiopian government representatives attended flag-raising ceremony in Addis Ababa
Turkish Energy experts have said that Russian claims that Turkey was operating on an oil delivery to Turkey before it was downed, are ridiculuous
The Burkina Faso election is scheduled for this upcoming Sunday
Two suspects were taken into custody in connection with Mali hotel attack that killed 19 people
British PM pledges £1 million ($1.5 million, 1.4 million euros) a year over five years to establish and support a new Commonwealth counter-extremism unit
Russia has decided to suspend visa-free regime with Turkey starting from January 1, 2016
President Hollande vows to crush 'army of fanatics' with more 'songs, concerts and shows'
'At the moment, unfortunately, our partners are not ready to work within the format of single coalition,' Putin's spokesman says
The clashes took place between Rwandan rebels and a local Mai-Mai militia
Russian president says they will work with regional countries not to target 'moderate opposition' groups
French foreign minister suggests possible cooperation with Syrian regime forces against ISIL
Two presidents agreed to 'exchange information about which territories are occupied by the healthy part of the opposition rather than terrorists, and will avoid targeting them with our airstrikes'