Four people have been killed and at least 30 injured in protests linked to Kenya's nationwide transport strikes against recent increases in the cost of fuel, according to the interior minister.

Thousands of commuters were left stranded, with key roads in the capital, Nairobi, largely empty as some businesses remained shut and schools asked students to stay at home.

Protesters have been blocking roads and erecting burning barricades. Interior Minister Kipchumba Murkomen added that 348 people had been arrested.

The strike comes days after the authorities raised petroleum prices to record levels, with costs increasing by more than 20%.

Kenya, like many other African countries, relies heavily on fuel imports from the Gulf, a supply route disrupted by the US-Israel conflict with Iran that began on 28 February. Even though a ceasefire has been declared, fuel prices have remained high as the Strait of Hormuz, where a fifth of the world's oil passes through, is still blocked.

Many passengers were stranded at bus stops in the capital in the morning. Others arriving from elsewhere to Nairobi could not get into the city.

"There is no matatu anywhere... We used to pay 100 to 150 shillings, right now it's 300. Life is becoming so unbearable. So please, [President William] Ruto, wherever you are, if you can listen to us Kenyans, please lower those fuel prices," a resident of Kitengela on the outskirts of the city, who identified himself as Charles, told the Reuters news agency.

The conductor of a bus carrying passengers from Tanzania said they could not get to Nairobi in the morning because of roadblocks and were stranded in Kajiado, a town about 75km (46 miles) from the city.

"The bus was full. Many passengers were travelling for work and business. People are now stranded and frustrated because transport has been disrupted," he told the BBC.

Abdi Suleiman, a motorist who operates in the south-eastern Kenyan border town of Taveta and sources food items from across the border in Tanzania, told the BBC that he was unable to supply them as usual since morning because of the strike.

In parts of Nairobi and elsewhere across the country, police used tear gas to disperse protesters who had blocked roads with burning tyres and barricades, amid reports they had been stopping and harassing motorists.

Nairobi police commander Issa Mohamud said six police officers were injured in the clashes, and five police vehicles and one civilian vehicle were damaged.

Ahead of the strike, the police assured Kenyans that security measures would be in place and warned against any disruptive conduct.

Speaking to reporters on Monday evening, Murkomen said it was "unfortunate that today's protests have once again been hijacked by political actors for political ends".

"Looting businesses and vandalising public property can in no way bring down oil prices," Kenya's news website, Kenyans, cited him as saying. "Disrupting transport and destroying livelihoods will only worsen the situation facing Kenyans."

Murkomen added that most of the roads had been cleared.

The association representing transport operators had earlier urged all vehicle users, including private motorists, public transport buses (locally known as matatus) and truckers, to stay off the roads as part of a coordinated shutdown.

"This action is not only for transport operators, but for every Kenyan citizen," the Transport Sector Alliance (TSA) said in a statement.

The alliance has accused the government of not doing enough to shield Kenyans from the rising fuel prices, amid a broader high cost-of-living crisis.

It has called for the reversal of the price increases announced last week, and for fuel prices to be reduced by about 35%.

The Energy and Petroleum Regulatory Authority (Epra) on Thursday raised prices to a high of 242 shillings ($1.8; £1.4) a litre for diesel and petrol to $1.65.

Treasury Minister John Mbadi told local NTV station on Monday that the increase in fuel prices was "unfortunate" and acknowledged that it was hurting the economy.

He however said the strike was "completely uncalled for" and the government would only make decisions that are "informed and not emotional".

"Why are we trying to solve a global problem using domestic means?" he asked.

The high cost of fuel is being blamed for increases in the price of food and other basic goods and services, with public service vehicles already raising commuter fares.

Last month, the government cut VAT on fuel from 16% to 8% until July but there have been calls for it to do more.

Mbadi added that the government may consider further tax relief measures if global prices continue to rise.

But no agreement has been reached between the government and transport operators, raising fears the strike could continue.