Hello, I'm Neil Nunes with the BBC news.

Ukraine is holding ceremonies to mark the 30thanniversary of Chernobyl, the world's worst nuclear accident. Siren sounded at the exact moment of the first explosion in the plant's reactor in April 1986, from Ukraine, Tom Burridge. “Candles were lit and prayers were set in the early hours of this morning. At the moment 30 years ago, that there was an explosion inside reactor 4 at the Chernobyl Nuclear plant. Roughly 3% of the reactor’s radioactive content escaped. Later Ukraine's president will attend another ceremony in Chernobyl to mark the disaster which contributed to the downfall of the Soviet Union and had a huge impact on public opinion and government policy towards nuclear energy.”

The influentially Iraqi cleric Muqtada al-Sadr has called for a big protest today in Baghdad over the simmering political crisis. They take place as parliament makes a fresh attempt to vote on a new cabinet after three weeks of stalemate. Ahmed Maher is in Baghdad. “It is the worst political crisis since the downfall of former dictator Saddam Hussein in 2003. For the past three weeks, parliament has refused to approve a new line-up of non-partisan ministers proposed by the embattled Prime Minister Haider al-Abadi. More than 100 MPs have been staging a sit-in in parliament since mid-April to express their frustration at other representatives who blocked the vote, the even vote to sack the speaker of parliament.”

The Canadian Prime Minister Justin Trudeau has expressed outrage of the killing of John Ridsdel, a Canadian hostage kidnapped by Islamist militants in the Philippine six months ago. Earlier in the day, the former mining executive severed head was found in the street on a remote island. The Islamist militant group Abu Sayyaf had demanded a large ransom for his release. Chrisaudi Arbes, a journalist who specializes in the threat posed by extremist group in the region of Mindanao, says the killing is part of a change of strategy for the militants. “They've become really bolder. This is the second time they’ve killed a foreigner. That wasn't the case before. It wasn't like that in the past. So this one is like a message from them saying we're going to do what we want to do because we know we can get the money and this is our way to fight against the military.”

A study in Britain suggests that flu vaccines are more effective when they’re given in the morning rather than the afternoon. Researchers found that antibody response was stronger in those vaccinated before 11:00 AM. They say that immunizing people in tune with the body's natural rhythm could also help improve vaccination strategies more generally and save lives. The study was based on people over the age of 65.

World news from the BBC.

Thousands of demonstrators have been bussed into the state capital of North Carolina in the US to either support or oppose a new state law that imposes restrictions on transgender people. The law demands that people use toilets in public buildings and schools that match the sex on their birth certificate rather than their gender identity. Both President Obama and the Republican presidential contender Donald Trump say the law is discriminatory.

The Venezuelan Supreme Court has rejected a constitutional reform proposed by opposition politicians who wanted to reduce President Nicolás Maduro's term in office from six to four years. Leonardo Rocha has more details. “Since the Venezuelan opposition regained control of parliament in December's election, it has made different attempts to oust President Maduro. It first tried to call a referendum to remove Mr. Maduro from office, but that was blocked by the electoral council. The opposition blames the leftwing policies of Mr. Maduroand his predecessor Hugo Chávez for the shortage of food and basic items, high inflation and violence. But Mr. Maduro says he will carry on in the next three years with his program of socialist reforms.”

A French cardinal accused of covering up child sex abuse by priests has acknowledged that his diocese made some mistakes and that victims had a right to truth and justice. Cardinal Philippe made his statement after a meeting in Lyon of more than 200 priests who had heard from a victim of Bernard Prey at, a priest who has admitted sexually abusing young boys over 25 years ago.

Researchers have come up with a theory that bed bugs have favorite colors, red and black, and dislike white and yellow. The insects were placed inside petridishes and given a choice of different-colored bug size tents to hide in. The revelation could lead to better bed bug traps.

That's the latest BBC world news.